BAC TRIA, the ancient name of the imperfectly known land lying between the western part of the Hindu Kush mountains, and the river Oxus (Amu, or Gihon), which separated it from Sogdiana on the n. and n.e. Its boundaries in early times ,can not be precisely ascertained, but it is generally considered to have been identical with the modern Balkh (q.v.). B. is supposed to have been the seat of the parent-people from which the zvryan (q.v.) or Indo-European family of nations branched off. The ancient Bactrians of historic times were akin to the 3Iedes and Persians, and used the Zend language. B. was originally the center of a powerful kingdom, which oAtended itself over the e. of Persia, but we have ahnost no record of its early greatness; we only know that sinus, the Assyrian king, in spite of his vast army, found much difficulty in conquering it, and that when Arbaces besieged the last Assyrian king, Sardanapalus, iu his metropolis, lie was assisted by a large force of Bactrians. It is believed that the ancient Persian religion was first developed in Bactra or Zariaspa, the capital of B.,
which was the head-quarters of the .Magi till the land was overrun by the Arabs, and a center-point of the inland trade of Asia. The modern town of Balkh (q.v.) is built upon its site. Alexander, on his return from Persia, left in B. a colony of 14,000 Greeks, who here extended civilization. After the death of Alexander, B. was annexed to the king dom of Syria; but was raised to independence by its governor, Diodotus I., who founded the Greek kingdom of new B. about 256 B.C. The history of this kingdom was formerly little known, but has been recently elucidated by numerous Graceo-Bactrian coins found in the topes or burial-places of Afghanistan. These coins give the names of a series of kings, and bear indications of the political circumstances of the Greek king dom of B. On those of Eucratides, a monarch•who flourished in the age of 3lithridates, there are found, beside the Greek characters, others which have been proved to belong to a dialect of the Sanscrit, and have been very happily deciphered by Mr. Prinsep.