While the semi-arid plains were dominated by the nomads, small city-states and sedentary agrarian societies arose in the more humid areas of Central Asia. The Bactria-Margiana Archaeological Complex of the early 2nd millennium BC was the first sedentary civilization of the region, practicing irrigation farming of wheat and barley and possibly a form of writing. Bactria-Margiana probably interacted with the contemporary Bronze Age nomads of the Andronovo culture, the originators of the spoke-wheeled chariot, who lived to their north in western Siberia, Russia, and parts of Kazakhstan, and survived as a culture until the 1st millennium BC. These cultures, particularly Bactria-Margiana, have been posited as possible representatives of the hypothetical Aryan culture ancestral to the speakers of the Indo-Iranian languages (see Indo-Iranians).