or Bactriana, now Chorassan or Khoreasan, an ancient kingdom of Asia, bounded on the west by Margiana, on the north by the river Oxus, on the south by Mount Paropamisus, and on the east by the Aastic Scythia and the country of the Massagetae. It was a large, fruitful, and well-peopled country, containing according to Ammianus Marcellinus 100 cities, though of these only a few are particularly mentioned by historians, of which that formerly called Maracanda, now Samarcand, is the most considerable.

Of the history of this country we know but little. Authors agree that it was subdued first by the Assyrians, afterwards by Cyrus, and then by Alexander the Great. Afterwards it remained subject to Seleucus Nicator and his successors till the time of Antiochus Theos; when Theodorus, from governor of that province, became king, and strengthened himself so effectually in his kingdom, while Antiochus was engaged in a war with Ptolemy Philadelphus king of Egypt, that he could never afterwards dispossess him of his acquisitions. His posterity continued to enjoy the kingdom.