The most accepted theory is the one by the Greek geographer Strabo: according to him, Arsaces was a Scythian or a Bactrian chieftain, who became the leader of the Parni, one of the three tribes of the Dahae confederacy of Central Asia. The Dahae relied their strength completely on horseback, and thus possessed an extremely mobile force, which was able to retreat to the south of the Aral Sea when endangered. Because of this, other empires met complications in their efforts trying to control them.