 Complete the following phrase:  Before Greek conquest, the armies of Bactria were overwhelmingly composed of cavalry and were well known as effective soldiers, making up large portions of the Achaemenid cavalry contingents. 2,000 Bactrian horsemen fought at the Granicus against Alexander and 9,000 at the Battle of Gaugamela on the left flank of Darius army. Herodotus also mentions the widespread use of chariots among the Bactrians. After Alexanders conquest of Bactria, Bactrian cavalry units served in his army during the 