Iranian plateau
The later Neo-Elamite period is characterized by a significant migration of Indo-European speaking Iranians to the Iranian plateau. Assyrian sources beginning around 800 BC distinguish the "powerful Medes", i.e. the actual Medes, Persians, Parthians, Sagartians, Margians, Bactrians, Sogdians etc.. Among these pressuring tribes were the "Parsu", first recorded in 844 BC as living on the southeastern shore of Lake Urmiah, but who by the end of this period would cause the Elamites' original home, the Iranian Plateau, to be renamed Persia proper. These newly arrived Iranian peoples were also conquered by Assyria, and largely regarded as vassals of the Neo-Assyrian Empire until the late 7th century.