In the history of the ancient world, Bactria is somewhat of an anomaly: a Greek kingdom located in modern Afghanistan. When Alexander the Great conquered the Persian Empire, he acquired all its outlying provinces including Bactria. Greek forces then established and maintained control in Bactria. After Alexander’s death, his kingdom was divided among his generals and Bactria became part of the eastern section, ruled by the Seleucid Dynasty. There was extensive immigration of Greeks who found several cities based on the Greek model complete with gymnasiums and amphitheatres. Later, the Greco-Bactria Kingdom asserted its independence and quickly expanded its holdings to the upper reaches of the Indus River Valley. The Greek Kingdom in Bactria lasted for another two centuries, until it was finally overwhelmed by nomadic tribesmen invading from the central Asian steppes.