The Tinajas Altas Mountains are an extremely arid northwest–southeast trending mountain range in southern Yuma County, Arizona, approximately 35 mi southeast of Yuma, Arizona. The southern end of the range extends approximately one mile into the northwestern Mexican state of Sonora on the northern perimeter of the Gran Desierto de Altar. The range is about 22 mi in length and about 4 mi wide at its widest point. The highpoint of the range is unnamed and is 2,766 feet above sea level and is located at 32°16'26"N, 114°02'48"W. Aside from the portion of the range in Mexico, the entirety of the range lies within the Barry M. Goldwater Air Force Range. They lie at the heart of the traditional homeland of the Hia C-eḍ O'odham people.

The Gran Desierto de Altar is one of the major sub-ecoregions of the Sonoran Desert, located in the State of Sonora, in northwest Mexico. It includes the only active erg dune region in North America. The desert extends across much of the northern border of the Gulf of California, spanning more than 100 kilometres (62 mi) east to west and over 50 kilometres (31 mi) north to south. It constitutes the largest continuous wilderness area within the Sonoran Desert.