The Chihuahua is the only breed of dog truly indigenous to the Western Hemisphere. Legend and history are rich in tales of the ancestors of the present Chihuahua. The breed's name indicates the ancestors of the dog came from the state of Chihuahua in Mexico. However, the breed's origins more properly belong to the southern part of Mexico or to the whole of the country rather than to the specific state that bears its name.

It is thought that the Chihuahua is derived from an earlier breed known as the Techichi, which was popular during the Toltec period around the seventh century. This breed was well known among the Aztecs as well as the Toltecs.

Legend has it that the Chihuahua was also involved in the religious worship of the Aztecs. The dog was presumed to have the power of leading the dead through the fearful regions of the underworld. When a dog was sacrificed at the time of the death of a human, the sins of the human were supposed to be transferred to the animal that appeased the gods. The pyramids of Cholula, Mexico are of Toltec construction. One finds here some carvings of the early specimens of the breed.