The Juan Bautista de Anza Expedition of 1775-1776 traveled 1,800 miles from Sonora, Mexico, to Monterey, California, with 240 settlers, soldiers, and others. Anza then continued with a much smaller group to San Francisco and the East Bay to discover the origins of the water of both San Francisco Bay and the Central Valley and to find a route eastward to the Sierra Nevada Mountains. On April 4, 1776, the explorers came very close to this area, but the impenetrable marshes and waterways of the Delta to the east forced them to turn south back to Monterey. Near this site on April 3, 1776, Father Pedro Font recorded in his diary his confirmation that the Central Valley was a lake, though it is now understood to have been a complex mosaic of rivers and marshes rich with life that flooded with winter rains and spring snowmelt from the Sierra Nevada Mountains. Future generations after Anza also treated the Delta wetlands as a hindrance and diverted most of its water for use elsewhere, drying the land for farming and development. This area is in the homeland of the Julpun, a Bay Miwok-speaking tribe.