The city of Alexandria on the Oxus, possibly later named Eucratidia and known today as Ai Khanoum, was founded in the 4th century BC, following the conquests of Alexander the Great and was one of the primary cities of the Greco-Bactrian kingdom.
Ai Khanoum was one of the focal points of Hellenism in the East for nearly two centuries, until its annihilation by nomadic invaders around 145 BC about the time of the death of The Bactrian Eucratides. Bactria's defeats, both in the west against the Parthians and the east against the Indo-Greeks, may have left Bactria very weakened and open to the nomadic invasions.
The invading Indo-European nomads from the north (the Scythians and then the Yuezhi) crossed the Oxus and submerged Bactria about 135 BC. It seems the city was first sacked by the Saka, then totally abandoned between 130-120 BC following the Yuezhi invasion. There is evidence of huge fires in all the major buildings of the city. The last Greco-Bactrian king Heliocles moved his capital from Balkh around 125 BC and resettled in the Kabul valley. No coins of Heliokles have been found in Ai-Khanoum, suggesting the city was destroyed at the end of the reign of Eucratides. The Greeks continued to rule various parts of northern India under the Indo-Greek Kingdom until around 10 CE, when their last kingdom was conquered by the Indo-Scythians. Only a few decades later, the Yuezhi united to form the Kushan Empire and expanded in northern India themselves
