Small groups of nomadic, horse-riding peoples speaking Indo-European languages began moving into the Iranian cultural area from Central Asia near the end of the second millennium B.C. Population pressures, overgrazing in their home area, and hostile neighbors may have prompted these migrations. Some of the groups settled in eastern Iran, but others, those who were to leave significant historical records, pushed farther west toward the Zagros Mountains.

Three major groups are identifiable--the Scythians, the Medes (the Amadai or Mada), and the Persians (also known as the Parsua or Parsa). The Scythians established themselves in the northern Zagros Mountains and clung to a seminomadic existence in which raiding was the chief form of economic enterprise. The Medes settled over a huge area, reaching as far as modern Tabriz in the north and Esfahan in the south. They had their capital at Ecbatana (present-day Hamadan) and annually paid tribute to the Assyrians. The Persians were established in three areas: to the south of Lake Urmia (the tradional name, also cited as Lake Orumiyeh, to which it has reverted after being called Lake Rezaiyeh under the Pahlavis), on the northern border of the kingdom of the Elamites; and in the environs of modern Shiraz, which would be their eventual settling place and to which they would give the name Parsa (what is roughly present-day Fars Province).

During the seventh century B.C., the Persians were led by Hakamanish (Achaemenes, in Greek), ancestor of the Achaemenid dynasty. A descendant, Cyrus II (also known as Cyrus the Great or Cyrus the Elder), led the combined forces of the Medes and the Persians to establish the most extensive empire known in the ancient world.

Data as of December 1987