Garcés became a key player in this effort, conducting extensive explorations in the Sonoran, Colorado, and Mojave Deserts, the Gila River, and the Colorado River from the Gulf of California and Lower Colorado River Valley to the Grand Canyon. He encountered and recorded accounts of the Native American tribes in their desert and riparian valley homelands, and established peaceable relations for the Crown, including with the Quechan, Mojave, Hopi, and Havasupai. Many journeys were explorations on his own in the deserts. He accompanied soldier-explorer Juan Bautista de Anza part way in both his large overland expeditions: the 1774 De Anza Expedition - first to reach Alta California's Pacific coast from the east; and the 1775-76 Anza Colonizing Expedition, which traveled as far north as San Francisco Bay. Garcés also crossed the Mojave Desert on the Mohave Trail and then the Old Tejon Pass and explored the southern San Joaquin Valley in 1776. The eastern part of the route Garcés took from the Colorado River across the Mojave Desert is known to four-wheel-drive adventurers today as the Mojave Road.