559-530 BC -- Cyrus the Great established the Persian Empire in 550 BC, the first world empire. His respect for local traditions, laws, languages, and religions set the foundation of a relatively benevolent empire.

539 BC -- Babylonia surrendered peacefully to Cyrus the Great. Welcomed as a liberator because of his compassionate policies, Cyrus freed the Jews from captivity and assisted them to migrate to their homeland and to reconstruct their temple in Jerusalem. In the Old Testament, in the Book of Isaiah, Cyrus is hailed as the Shepherd of the Lord. I am Cyrus, King of the World. When I entered Babylon I did not allow anyone to terrorize the land. I kept in view the needs of its people and all its sanctuaries to promote their well being. I put an end to their misfortune. The great God has delivered all lands into my hand, the lands that I have made to dwell in peaceful habitation.

522-486 BC -- The reign of Darius the Great marked the zenith of the Persian Empire. Upholding the tradition established by Cyrus, Darius valued the rights of all people under his rule. The following inscription appears on his tomb: By the favor of the great God I believe in justice and abhor inequity. It is not my desire that the weak man should have wrong done to him by the mighty....Darius' goal was to be a great law-giver and organizer. He structured the empire under the satrapy system (similar to national and local governments). He built many roads, ports, banking houses (the word "check" comes from Old Persian), elaborate underground irrigation systems and a canal to link the Nile to the Red Sea (an early precursor of the Suez Canal). In the 19th century, archeologists in Egypt discovered an inscription by Darius commemorating the completion of the canal: I am a Persian. I commanded to dig this canal from a river by name of Nile which flows in Egypt....After this canal was dug, ships went from Egypt through this canal to Persia, thus as was my desire.

Darius revolutionized mankind's economic activities by introducing one of the earliest (certainly the first on such a massive scale) forms of common coinage in history, the darik. This initiative, along with the standardization of weights and measures and the codification of commercial laws, stimulated world trade and elevated the Persian Empire's economy to new levels of prosperity.

Reflecting the wealth and the multi-cultural dimension of the Persian Empire, Darius initiated the building of the Persepolis palace. For its construction, artisans and materials were gathered from different corners of the empire. Another project undertaken by Darius was the royal road, the world's longest, extending 1,500 miles (see map). Due to an extensive network of relays, postmen could travel the road in six to nine days, whereas normal travel time was three months. The motto of the Persian postal service became memorable: stopped by neither snow, rain, heat or gloom of night. The US postal service also adopted this motto and the famous Pony Express mail delivery resembled the original Persian design. The origins of polo date back to this time. Persian nobility played an early form of polo for both sport and combat training.

490-479 BC -- In their wars with Persia, the Greek city-states were never a threat to the Persian heartland. What Persia did not achieve through war, it obtained through diplomacy. After the Persian-Greek wars ended, Persian kings successfully played the Athenians and Spartans against each other for 150 years. Persia's financial and naval assistance was instrumental in Sparta's victory over Athens in the Great Peloponnesian War. Afterwards, Persia began supporting the Athenians. The Persian influence over the two Greek city-states was such that the Persian King Artaxerxes II was asked to mediate between them, leading to the King's Peace of 387 BC.

550-334 BC -- The Persian Empire became the dominant world power for over two centuries. It made possible the first significant and continuous contact between East and West. It was the world's first religiously tolerant empire and consisted of a multitude of different languages, races, religions and cultures. Prior to the rise of the Roman Empire, it set a precedent for the importance of the rule of law, a powerful centralized army and an efficient and systematic state administration. However, the greatest legacy of the Persian Empire was that it demonstrated for the first time how diverse peoples can culturally flourish and economically prosper under one central government.

334 BC -- Alexander Invaded Persia. After his victory over the Persian army, he ordered the execution of many Persians, allowed his troops to indulge themselves in plunder and rape and, in a drunken rage, set torch to Persepolis. However, he also considered himself a successor to Achaemenian Kings and paid tribute to Cyrus the Great at his tomb. He emulated Persian court customs and attempted to create a new culture, a mixture of both Persian and Hellenistic. He married a Persian woman (Roxana) and ordered all his generals and 10,000 of his soldiers to follow suit in a mass wedding.

323 BC -- Alexander died. Although a masterful general, he lacked administrative skills. Shortly after his death, his empire was divided among his contesting generals. An important legacy of his conquest of Persia was the introduction of the Persian imperial practices into the West. Many of these practices ­ particularly those relating to state administration and the rule of law ­ were later adopted by the Roman Empire.

323-141 BC -- The Seleucid Dynasty was established by one of Alexander's generals.

247 BC-224 AD -- The Parthians, a tribal kingdom from northeastern Iran, gradually defeated the Greek Seleucids and consolidated their control over all of Persia. The name of the founder of the dynasty, Arsaces, became the title of all Parthian kings in much the same way that the name of Caesar was later to become the title of all Roman emperors. They fought numerous times with the Romans. Their victory over the Romans in 53 BC elevated the Parthians into a superpower of their era. The Romans were especially in awe of the expert mobile Parthian archers (hence the term: the Parthian Shot) who inflicted enormous casualties upon successive Roman armies. Although the Parthians ruled for almost five centuries, very little of their civilization has survived, except for some small art objects.

224 -- Ardeshir I founded the Sasanian dynasty. The Sasanians revived Persian culture and Zoroastrianism and made a conscious effort to return to the Achaemenian norms. They sponsored trade both with their arch-enemy, the Romans/Byzantines, and the Chinese. Excavations in China have unearthed gold and silver Sasanian coins covering a span of many centuries.

260 -- Shahpur I invaded the Roman Empire and took Emperor Valerian prisoner. He also established Jondi Shahpur, a major center of higher learning.

274 -- Mani, the founder of Manichaeism, tried to introduce a new universal world religion, combining elements of Zoroastrianism, Christianity and Buddhism.

528 -- Mazdak advocated abolition of private property, the division of wealth, as well as nonviolence and vegetarianism. His ideas brought about a major class struggle between the peasants and the nobility. He could be considered the world's first "communist/socialist."

531-579 -- The reign of Khosrow I (Anushiravan) marked the height of the Sasanian dynasty. He promoted scholarship and sponsored the translation of Indian and Greek scientific and medical texts into Middle Persian or Pahlavi, Persia's native language. By the time of Khosrow I, Jondi Shahpur's library had amassed one of the largest collections of books in the world. He also gave refuge and financial assistance to philosophers fleeing oppression in the Byzantine Empire. Khosrow I was also a populist king, possibly a reflection of Mazdak's ideology and the civil conflicts that subsequently ensued. He made himself available to all his subjects; anyone could rattle his chain of justice and have an audience with the king. His famous prime minister, Bozorgmehr, reportedly invented the game of backgammon.

570 -- The Prophet Mohammad was born.

608-622 -- The long war between the Sasanians and the Byzantines significantly weakened both sides.

622 -- Fearing persecution for his beliefs, the Prophet Mohammad migrated from Mecca to Medina. His migration or Hijra marked the birth of Islamic civilization and the starting point of all Islamic calendars. God conveyed the beliefs of Islam to the Prophet Mohammad through the angel Gabriel in a series of visions and revelations. Muslims consider the Prophet Mohammad as the last prophet in a line of prophets that includes the prophets Moses and Jesus.

629-632 -- Two consecutive female monarchs ruled over the Sasanian Empire, Purandokht and her sister Azarmidokht. Purandokht signed a peace treaty with the Byzantines.

632 -- The Prophet Mohammad died. Subsequently, his revelations were gathered and compiled into the holy book of Islam - The Koran.

After successfully defending itself against the Roman/Byzantine Empires for centuries, the Persian Empire was swiftly vanquished by nomadic tribesmen armed with a newly acquired faith, Islam. Islam's ideals of equality and unity appealed to many Persians, as they were in sharp contrast to the rigid and hierarchical social structure of the later Sasanian period. The five pillars of Islam consist of: 1) "There is no God but Allah, and Mohammad is the Prophet of Allah," 2) Prayer (to always be in touch with God), 3) Pilgrimage to Mecca (to have a sense of community and for the exchange of ideas), 4) Fasting (to feel the pain of the disadvantaged and to develop self-discipline) and 5) Alms or charitable contributions (to share one's blessings).

The main dividing point was the issue of Islamic leadership. Shi'ites believed in the divine right of the family of Mohammad through his daughter Fatima and her husband Ali to lead the Islamic world. Although Persia did not become a Shi'ite state for almost another nine centuries, this clash was pivotal in its history.

661-750 -- The Umayyad Caliphate emerged as the rulers of the Islamic world. Although they maintained the Sasanians' administrative practices, the Umayyads considered Islam as primarily an Arab religion and were wary of Persian culture. They tried to force the Arabic language upon the Persians, leading to the demise of the Middle Persian or Pahlavi alphabet in favor of the new Arabic/Persian alphabet in use to this day. They also tried to eradicate the independent and unique sense of Persian identity in the same way that they "Arabized" and assimilated the Egyptians and the Assyrians, but with minimal success.

680 -- Imam Hussein, Imam Ali's son, was killed by Umayyads in Karbala (one of Shi'ism's most holy sites) for refusing to recognize the legitimacy of their right to rule.

696 -- Arabic became the official language of the Islamic world.

750 -- With Persian financing and support, the Abbasids ended Umayyad rule. Their victorious armies were led by a Persian general named Abu Muslim Khorasani. The Islamic capital was relocated from Damascus to Baghdad, a newly built city adjacent to the old Sasanian capital, Ctesiphon. This relocation symbolized the rising power of Persians in the Islamic world.

750-1258 -- The Abbasid Caliphate relied on Persian ministers and bureaucracy for many state functions. Persian customs began to take deep roots under the Abbasids. The offices of the vizier (minister) and the divan (or bureau for state revenue) were copied from the Sasanian model and later caliphs adopted the Persian courts' ceremonial procedures and the trappings of the Sasanian kings. The Persian Barmakid family became architects of the Abbasid political structure and several members of their family became notable grand viziers. The Abbasid reign marked the pinnacle of the power and glory of the Islamic world.

820-1220 -- Arab rule over Persia began to diminish as various local Persian monarchs rose to power: the Tahirids (821-873), Saffarids (867-903), Samanids (873-999), Ziyarids (928-1077) and Buyids (945-1055). They were followed by Turkic dynasties with Persian culture: the Ghaznavids (962-1186), Seljuqs (1038-1153) and Khwarazmis (1153-1220). The modern Persian language was born and it soon blossomed into one of the most poetic languages of the world. The Samanids were the first to adopt Persian as the official language of their court. Once again, Persia became a world center for art, literature and science. Key figures in nearly all fields of endeavor in the Islamic world, Persians played a major role in the advancement of Islamic civilization.

840 -- Sibovayh, a Persian scholar, laid the foundation for the codification of Arabic grammar and wrote the first Arabic dictionary.

850 -- Khwarazmi, a remarkable mathematician and astronomer, wrote precise astronomical tables and the first work of algebra, The Book of Integration & Equation. The word "algebra" is derived from this book's title and the word "algorithm" from his own name. He helped establish the concept of zero and perfect the decimal system. The culmination of his work, along with that of other Islamic scholars, produced the Arabic numerals - a modified version of which replaced the Roman numerals in the West and which is still in use to this day.

879 -- Yaqub Leys was the first Persian ruler to openly revolt against the Arabs. He brought much of Persia under his control and promoted the Persian language.

865-925 -- Razi, one of the most accomplished physicians, chemists and philosophers of his era, invented the medical usage of alcohol and wrote a number of books on a variety of topics, especially medicine. One of his more famous treatises, On Small Pox and Measles, was translated into many European languages.

940 -- Rudaki crystallized the new Persian language and its lyrical poetry. He was the first major poet of the Persian language. His contribution was especially important since poetry was to become one of the main pillars of Persian culture and identity.

940-1020 -- Ferdowsi, Iran's national poet and possibly its greatest hero, completed the national Iranian epic, Shahnameh, The Book of Kings, in 1010. It took him 30 years and consisted of some 50,000 couplets. He was a genuine defender of Persian national identity and, while a devout Muslim, deeply resented the Arab influence. He wrote his entire epic story with minimal usage of Arabic-derived words. Shahnameh consists of mythical stories of pre-Islamic Persia. The book's chief epic hero is a noble knight named Rostam, who embodies values such as integrity, strength and chivalry.

980-1037 -- Ibn Sina (Avicenna), one of the most significant scientists and philosophers of the Islamic civilization, wrote over 200 books, including The Cannon of Medicine, an encyclopedia summarizing all the then known medical knowledge from across the world. This book was translated into Latin and remained the most influential book of medicine in the world until the 17th century. He was also a renowned philosopher who emphasized the use of logic and reason as means of discovering the truth.

945-1055 -- The Buyids, from north-central Iran, defeated the Arab armies and captured Baghdad. Although they allowed the Caliph to retain his title, they reduced the role of the Caliph to that of a religious figurehead. The Buyids held the actual political power in the eastern Islamic world for a century.

1092 · Nizam al-Mulk was the renowned prime minister of Malik Shah of the Seljuq dynasty. Under his guidance, Malik Shah controlled virtually the entire eastern segment of the Islamic world, from Syria to Afghanistan. Nizam al-Mulk wrote the Siyasatnameh, The Book of Government and Politics. He argued for the regulation of court procedures, a systematic decision-making process and the restriction of arbitrary rule. He also established the Nizamieh schools in the major cities under Seljuq rule. They became the leading institutions of higher learning in the Islamic world. He was the benefactor of both Ghazali and Khayyam.

1058-1111 -- Ghazali was recognized as the most prominent Muslim jurist and theologian of his time. He argued against a merely rational and logical interpretation of existence, in favor of a more mystic and spiritual understanding. He represented the view opposite to Ibn Sina's rationalism and significantly undermined the influence of Ibn Sina on later Islamic thought. He was an important intellectual pillar of Sufism. Sufis strive for a deeper understanding of life and a closer communion with God through meditation, inner self-examination and the rejection of worldly possessions.

1048-1122 -- Omar Khayyam, a great mathematician, poet and astronomer, performed the mathematical calculations to reform the Persian calendar, one of the most accurate calenders in the world and still in use to this day. He helped build an important observatory in Isfahan and wrote his collection of quatrains, Rubaiyat. Dealing with the great enigmas of human existence, his poems celebrate the divine gifts of love and life. The Rubaiyat was translated by FitzGerald in the 19th century, helping Khayyam to become the most famous oriental poet in Europe. His work has since been translated into many other languages and millions of copies have been sold.

1206 -- Gangis Khan united the Mongol clans and began his attempt at world conquest.

1220 -- Gangis Khan and his Mongol hordes attacked Persia with unparalleled brutality, bringing about one of the worst catastrophes in the history of mankind. In Persia's northeastern provinces, his descendants, especially Hulagu Khan, razed almost every major city, destroyed libraries and hospitals and slaughtered entire populations. The death toll estimates ranged in the millions.

1227 -- Gangis Khan died. His empire was divided among his sons.

1258-1353 -- The Mongols sacked Baghdad in 1258, thus ending the Abbasid Caliphate. The Il-Khanid dynasty gained control of the segment of the Mongol Empire covering Persia.

1271 -- Marco Polo journeyed through Persia on his way to China. In his Book of Travels, he wrote about the Mongols' savagery: How sad it is, the destruction, waste and death inflicted upon this once mighty, prosperous and beautiful Persia.

1207-1273 -- Rumi, the greatest mystical poet of the Persian language and the author of Mathnawi, elevated Sufism to unprecedented heights. Although a Persian, he lived in Anatolia (his parents had migrated in fear of the Mongols' brutality). His poetry and philosophy had a significant influence throughout the Islamic world. His disciples founded the famous Whirling Dervish mystic order.

1274 -- Nasir Al-Din Tusi, an astronomer and philosopher, built the Maraghah observatory, the first observatory in the modern sense in the history of science. He developed the mathematical calculations showing the earth's revolution around the sun and its spherical shape and size. His work was later translated into Latin and predated, by some 200 years, that of Copernicus, considered the founder of modern astronomy and the originator of the idea of a solar-centered universe.

1213-1292 -- Sa'di wrote two of the most significant Persian works, The Bustan and The Gulistan. His poems exercised wide influence in India, Central Asia and as far as the Muslims in China. His poems emphasized the interdependence of all mankind regardless of nationality, race or religion. He asked for the following inscription on his tomb: From the tomb of Sa'di, son of Shiraz - the perfume of love escapes - thou shall smell it still 1,000 years after his death.

1295 -- Ghazan Khan became the first Mongol Il-Khanid leader to convert to Islam. After his conversion, the Mongols, like the Greek, Arab and Turkic invaders before them, became "Persianized." Ghazan Khan's prime minister, Rashid ad-Din, was a Persian scholar who wrote one of the earliest works of universal history, Jami' Al-Tawarikh. After almost one hundred years of Mongol devastation, Rashid ad-Din's policies brought about a short-lived period of peace and prosperity. The vast Mongol Empire helped to facilitate the exchange of ideas and goods among China, India and Persia.

1320 -- Kamal Al-Din Farsi pioneered major advances in the field of optics with his theories on refraction and reflection.

1320-1390 -- Hafez, the greatest lyric poet of the Persian language, wrote his most famous work, The Divan. Hafez was a Sufi and his poetry is characterized by the sense of beauty, love of humanity and devotion to God.

1405 -- Timur (Tamerlane), a Turco-Mongol leader, conquered much of Persia and its surrounding areas. His conquests yet again consisted of unimaginable cruelty and devastation. Although brutal, he was also a patron of arts. He made Samarqand his capital and brought artists from all over Persia. After his death, his empire disintegrated, but his descendants ruled over various parts of Persia for almost a century.

1429 -- Jamshid Kashani, a major mathematician, advanced number theory, invented the first calculating machine and participated in the astronomical activities at Samarqand.

1501-1524 -- Shah Ismail I united all of Persia under Iranian leadership after some nine centuries of foreign or fragmented rule. Being a Shi'ite, he declared Shi'ism as the state religion and converted virtually all of Persia and some surrounding areas under his control from Sunnism to Shi'ism. Shi'ism became a medium for the Persians to differentiate themselves from the rest of the Islamic world, in particular from the Sunni Ottomans. To ensure its continuation as the state religion, the Safavid kings in general supported the Shi'ite clergy.

1587-1629 -- The reign of Shah Abbas the Great marked the pinnacle of the Safavid dynasty. He developed a disciplined standing army and defeated the Ottomans. In 1598, he chose Isfahan as his capital. A strong supporter of the arts, especially architecture, he adorned Isfahan with some of the finest Islamic monuments in the world. He built a number of mosques, schools, bridges and a major bazaar. During his reign, Persian craftsmen and artists excelled in creating fine silks, cloths, porcelain, metalwork, calligraphy, miniatures and carpets.

1501-1722 -- The two contemporary Islamic rivals of the Safavids, the Ottomans in Anatolia and the Mughals in India, relied on Persian artisans and poets for much of their arts and literature. Persian was the language of choice in both of their courts. This preference is evident from their poems and miniature paintings whose texts were almost exclusively written in Persian. Persian influence was especially prevalent in India, where it was also the cultural and administrative language; it remained so until the colonization of India by the British. The Taj Mahal's principle architect was a Persian named Ustad Isad and its architectural style was significantly influenced by Persian designs.

1722 -- Mahmoud Khan, an Afghan chieftain and a vassal of the Safavids, attacked Persia and captured Isfahan with virtually no resistance, thus ending the Safavid dynasty.

1795 -- Although the Qajars succeeded in reuniting the country, they were generally weak and corrupt rulers. The economic and military gap between Iran and the West widened considerably under their reign - especially in light of the Industrial Revolution that was taking place in the West. However, the Qajar period also enjoyed a high degree of artistic excellence, producing some of Iran's finest paintings, tileworks and architectural monuments.

1813 & 1828 -- European imperialism resulted in English and Russian penetration in Iranian affairs. The Qajars lost the Caucasus (present day Georgia, Armenia and Azerbaijan) to the Russians in two separate treaties: the Gulistan in 1813 and the Turkmanchay in 1828. As a result of the 1828 treaty, the Qajars were forced to enact the "Capitulation" law, exempting all foreign citizens from Iranian jurisdiction. This law deeply humiliated the Iranian people.

1851 -- Amir Kabir, a prime minister of the Qajars, tried to introduce many reform initiatives but was assassinated by his corrupt enemies within the court ­ a fate shared by an earlier reform-minded prime minister of the Qajars.

1851-1906 -- The Qajars lost central Asian provinces to the Russians and were forced to give up all claims on Afghanistan to the British. These two European powers dominated Iran's trade and manipulated its internal politics. The Qajars and influential members of their court were bribed to sell many valuable concessions to the British, such as the Tobacco Concession which triggered a massive popular uprising.

1906 -- Discontent with Qajar corruption and mismanagement led to the Constitutional Revolution and the establishment of Iran's first parliament or Majles. The constitutional aspirations for a limited monarchy were never to be fully realized. Although Iran never became an actual colony of imperial powers, in 1907 it was divided into two spheres of influence. The north was controlled by Russia and the south and the east by Britain. By the end of WW I, Iran was plunged into a state of political, social and economic chaos.

1921 -- Reza Khan, an officer in the army, staged a coup. Initially the minister of war and then the prime minister, in 1925 Reza Khan decided to become the Shah himself. Although Reza Khan's initial objective was to become the president of a republic, the clergy, fearing a diminished role in a republic, persuaded him to become the Shah.

1925-194 -- Reza Shah Pahlavi's first priority was to strengthen the authority of the central government by creating a disciplined standing army and restraining the autonomy of the tribal chiefs. He embarked upon a series of modernizing and secular reforms, some of which were designed specifically to break the power of the clergy over Iran's educational and judicial systems. He provided public education, built Iran's first modern university, opened the schools to women and brought them into the work force. He initiated Iran's first industrialization program and dramatically improved Iran's infrastructure by building numerous roads, bridges, state-owned factories and Iran's first Transnational railway. In 1935, he officially requested all foreign governments to no longer refer to Iran as Persia, but as Iran. (The Iranian people themselves had always referred to their country as Iran.) Politically, however, Reza Shah forcibly abolished the wearing of the veil, took away the effective power of the Majles and did not permit any forms of free speech. With the outbreak of WW II, Reza Shah, wanting to remain neutral, refused to side with the Allies.

1941 -- In need of the Trans-Iranian railway to supply the Soviets with wartime materials, the Allies invaded and occupied Iran for the duration of the war. Reza Shah was forced to abdicate in favor of his son Mohammad Reza Pahlavi and died in South Africa in exile in 1944.

1946 -- Under American pressure, the Soviet Union was forced to pull out of Iran's northwestern province. It was the first and only time that Stalin gave back a WWII occupied territory.

1951- 1953 -- Iran's Majles passed a law sponsored by the nationalistic (soon to be prime minister) Dr. Mossadeq to nationalize Iran's oil from British control. The British, enraged by the threat to their oil concessions, froze all of Iran's Sterling assets and took their case to the International Court of Justice. The Court ruled in Iran's favor. Undeterred, the British placed a total trade embargo on Iran and enforced it with their navy, leading to the collapse of Iran's economy. Citing the threat of a communist takeover, British Intelligence and the CIA sponsored a coup to topple Dr. Mossadeq's government. In the midst of the coup, the young Shah, having thought the plan had failed, left the country. Shortly thereafter, Dr. Mossadeq's government was overthrown and the Shah was put back in power.

1962-1963 -- The Shah introduced his White Revolution. It consisted of major land reform, workers' rights and women's suffrage, among other initiatives. His reforms did not develop as planned due to poor execution. In a series of public speeches, Ayatollah Khomeini attacked these reforms. He was arrested and then exiled.

1963-1973 -- Iran experienced rapid economic growth and prosperity coupled with a relatively stable political climate. Iran's infrastructure, public health and educational institutions were expanded. A number of highways, roads, bridges, railroad tracks, water and sewage projects, factories, schools, universities and hospitals were built. Iran's military strength grew and its international prestige was enhanced.

1973-1979 -- The oil embargo quadrupled Iran's oil revenue to $20 billion a year. This new wealth accelerated the Shah's timetable to make Iran "catch up" with the West. The Shah's determination to modernize Iran virtually overnight and at any cost led to cultural shock, alienation of the masses, inflation, corruption, economic bottlenecks, massive urbanization, rising expectations and increasing authoritarianism in dealing with these social, economic and political problems. By the late 1970s, the Shah's opponents, of all political affiliations, united behind Ayatollah Khomeini. The Shah was overthrown in 1979 by the Islamic Revolution and died in Egypt a year later. After 2,500 years of monarchy, Iran's government was changed to a theocratic republic, The Islamic Republic of Iran.