Indigenous peoples traveled into the mountains in the summer to hunt deer and rabbits, gather acorns, berries and nuts, and seek refuge from the desert heat. They established well-traveled trade routes, some of which were later used by Europeans to explore and settle the region. The precipitous Mojave Road (or Mojave Trail) crested the San Bernardinos east of Cajon Pass and permitted trade between people of the Inland Empire basin and the Mojave Desert. San Gorgonio Pass, which forms the largest natural break in the Transverse Ranges, also allowed interaction between coastal and desert tribes. River canyons, especially those of the Mojave and Santa Ana, provided the major means of entry to the mountains. Many archaeological sites have been discovered along Deep Creek, a tributary of the Mojave River, in particular.