For at least two thousand years before the arrival of Europeans, the San Bernardino Valley was populated by Shoshonean people, mostly Serrano and Cahuilla, who shared common ancestry, some language, and cultural traditions. They were hunter-gatherers who lived on acorns, roots, berries, fish, reptiles, and small game. During the summer months, groups migrated to higher ground, hunting and gathering in areas like Barton Flats and Bear Valley. Because the valley is part of a semi-arid and sub-tropical desert, rain was infrequent and the creeks often ran dry. The people were not farmers, and they survived with very little water by using creeks in season and sometimes digging shallow wells in dry creek beds.