The Iranian plateau was inhabited by a hunting and gathering group by 10,000 B . C . Around 3000 B . C ., waves of pastoralists from Eurasia drifted into the area searching for new pastures. Some of these pastoralists were warriors on horseback who supplanted the indigenous populations of the Iranian plateau. The first Iranians (Aryans) arrived about 1,000 B . C . They also penetrated the Iranian plateau in waves lasting several centuries, and, like their predecessors, they were pastoralists who also relied on agriculture to some extent.
The Iranians consisted of several tribal groups, including the Medes, Persians (Pars), Parthians, Bactrians, Soghdians, Sacians, and Scythians. For several centuries they absorbed the cultural influences of existing civilizations. In the seventh century B . C . they began to take over the known world. Between 625 and 585 B . C ., the Medes developed a powerful civilization, with its capital at Ecbatana, modern day Hamadān. They defeated the powerful Assyrians and sacked their capital, Nineveh, in 612 B . C . Those tribes that had settled near Lake Urmia moved south and occupied Persis (Parsa), the modern province of Fārs, from which they obtained their name. These loosely federated Persian tribes became a more cohesive political unit under the Achaemenian dynasty. In 553 B . C ., Cyrus, the ruler of Persis, overthrew the Median dynasty and consolidated the Medes and Perstans into the mighty Achaemenid Empire.
For 1,200 years Persia maintained a culture that grew increasingly complex and rigid. The social structure supported rulers, priests, warriors, artisans, scribes, pastoralists, agriculturists, and other producers. By the seventh century A . D ., a small privileged class dominated a large mass of people who were blocked from attaining any upward social mobility; this was an important factor in setting the stage for a successful Arab conquest.
In the thirteen centuries since the Arab invasion, there has been a steady Persianization of the society. Persians have been able to maintain their independence from invaders and their dominance over non-Persian minorities. An intense nationalistic movement began in 1925, which included the official adoption of the name "Iran," the use of Farsi as a national language, and government encouragement to produce the best in Persian culture.