Before Europeans arrived, Native Americans in the San Mateo area were known as the Salson, a group classified with the Ohlone or Costanoan people. The Salson triblet was the largest of several small groups in a region extending from present-day South San Francisco to Belmont and from San Francisco Bay to the foothills of the Santa Cruz Mountains. When the first Spanish explorers arrived, the largest Salson village stood behind the present Crystal Springs Dam. The Salson lived in tule houses framed with native willows growing along creek banks and roofed with marsh reeds. They lived in a region with a mild climate, abundant game and vegetation, and fresh water from nearby San Mateo Creek, one of the larger freshwater creeks on the west side of the Peninsula. They hunted deer, rabbit, elk, antelope, and birds with bow and arrow, snares, and traps, and they also fished for salmon and sturgeon and gathered shellfish, berries, seeds, and acorns to supplement their diet.