"The unsettled political conditions apparently encouraged clandestine diggings, and it seems that the ancient Bactrian region, centred in the Oxus valley which lies to the north of the Hindukush range, has been a good source of trade in illicit antiquities. In fact, the looted Bactrian graves, or rather, their antiquities surfacing in the western market, have been the major factor behind the postulate of an Oxus Civilization from the second half of the third millennium BC to about the middle of the second millennium BC."