The name Persia (from the ancient province of Persis; modern Fars, Iran) was given by the Greeks to the entire land occupied by various Iranian tribes from which the Achaemenid dynasty arose. It is the land of present-day Iran, geographically the Iranian plateau.

The earliest inhabitants of this area are only known, at first, from their stone artifacts and, later, their pottery. Paleolithic and Neolithic sites have been found in various parts of the plateau, but distinctive painted pottery appears only in the Chalcolithic Period, about 3000 BC. In sites such as Tepe Sialk, Tepe Hissar, and Tepe Giyan similar painted pottery has been found, indicating early connections among the inhabitants. More is known about the material culture of the peoples on the plateau in the 3d millennium BC, but the various groups assume an historical identity only with the advent of written records in cuneiform. In the south were the Elamites, whose principal city, Susa, was on the plain of Mesopotamia. The Elamite language has not been fully deciphered, but it was unlike any of the later languages of the region. In the 2d millennium BC the Elamites were found throughout southern Iran. To the north in the mountains lived Kassites who also descended onto the plains of Mesopotamia. In present-day Azerbaijan province lived people called Manneans. South of the sea that bears their name lived the Caspians.

Thus the western part of the Iranian plateau was inhabited by various peoples whose relationships to each other and whose languages are hardly known. The art objects of these peoples, some of which are made of gold and silver, reveal the high material culture then existing. Bronze objects from Luristan, mostly from graves, are evidence of great artistic originality. In eastern Iran archaeological excavations are only beginning to reveal evidence of settlements and civilization.

By the end of the 2d millennium BC invaders from the north had begun to spread over the Iranian plateau. These were Indo-European speakers, one branch of which invaded the subcontinent of India while their close relatives the Iranians penetrated the plateau. Both the Indians and Iranians called themselves Aryans. They had war chariots pulled by horses, but the Iranians soon found that cavalry was more effective in mountain areas. By the 9th century they had entered the Zagros Mountains; the Medes, the most prominent of the Iranian peoples, are mentioned as being there by Assyrian sources in 836 BC. More than a century later the Parsa, or Persians, appeared in the south. Other Iranian tribes spread over the entire plateau.