The ancient Sacae, or Scyths, are recognized in the Aryan population, who may be found in great numbers and in their purest form in the more inaccessible mountains and glens of the central highlands.
When about 255 B.C. Diodotus had made himself king of Bactria and tried to expand his dominions, the chieftain of a tribe of Iranian nomads (Dahan Scyths) east of the Caspian, the Parni or Aparni, who bore the Persian name Arsaces, fled before him into Parthia.
These tribes raised wheat, presumably in the river valleys, and sold it for export; in the eastern half from west to east were Georgi (perhaps the same as Aroteres) between the Ingul and the Borysthenes (Dnieper), nomad Scyths and Royal Scyths between the Borysthenes and the Tanais (Don).
From this region started an important trade route eastward by the Thyssagetae among the southern Urals, the Iyrcae on the Tobol and Irtysh to the Kirgiz steppe, where dwelt other Scyths, regarded as colonists of those in Europe: then by the Argippaei in the Altai and the Issedones in the Tarym basin, to the one-eyed Arimaspi on the borders of China, who stole their gold from the watchful griffins, and who marched with goat-footed men and Hyperboreans reaching to the sea.
- Herodotus expressly divides the Scythians into the Agriculturists, Callipidae, Alazones, Aroteres and Georgi in the western part of the country, and the Nomads with the Royal Scyths to the east.