the steppe region had long been inhabited by nomads, and from the central steppes they could reach all areas of the asian continent. the earliest known expansion out of the steppe is that of the indo-europeans which spread their languages into the middle east, the indian subcontinent, and in the tocharians to the borders of today's china. the northern part of the continent was not accessible to the steppe nomads due to the dense forests and the tundra. these areas had very few people.