The Azteca was first developed in Mexico in 1972, from a blend of Andalusian, American Quarter Horse and Mexican Criollo bloodlines.

[6] In Mexico, Azteca horses must conform to a strict phenotype standard established by the Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (SAGARPA), the Mexican agriculture ministry, which requires inspection of foals at seven months for the issue of a "birth certificate"; a foal that does not meet the breed standards may be denied registration even if both parents are registered Aztecas approved for breeding.

Full registration and approval for breeding are subject to a second and more detailed inspection at age three or more, and granted only to those horses that fully satisfy the requirements of the standard.

[5] American Aztecas have four categories of registration based on the relative degree of blood from each foundation breed, seeking an ideal blend of 3/8 Quarter Horse and 5/8 Andalusian.

[9] Early in the Azteca's history, breeders realized the need for a unified breeding program in order to produce horses that met the required characteristics.

The Azteca Horse Research Center was created at Lake Texcoco, and in partnership with breeders developed the phenotype of the breed today.

The majority of Aztecas are found in Mexico, and the Mexican association had registered between 10,000 and 15,000 horses as of 2005, according to the Texas Department of Agriculture.

[11] This registry has slightly different registration and breeding rules, and is not approved by the Mexican government to register Azteca horses.

The Mexican registry allows only the blood of Quarter Horses, Andalusians and Criollos in its registered Aztecas.