It is probable that Cyrus had fought more than one war against the peoples of eastern Iran; according to Ctesias he had, before the war with Croesus, defeated the Bactrians and the Sacae (in Ferghana; their king Amorges is the eponym of the Amyrgian Sacae, Herod.
But a great Bactrian empire certainly never existed; the Bactrians and their neighbours were in old times ruled by petty local kings, one of whom was Vishtaspa, the protector of Zoroaster.
Of their populations Herodotus mentions the Bactrians, Chorasmians, Sogdians and Sacae as contributing their contingents to the armies of the great king Darius.
Christianity penetrated to Khorasan and Bactria at an early date; episcopal sees are said to have existed at Mer y and Samarkand in the 4th and 5th centuries, and Cosmas (c. 545) testifies to the spread of Christianity among the Bactrians and Huns.
The Bactrians (Pers.