Chihuahuas remained a rarity until the early 20th century, and the American Kennel Club did not register a Chihuahua until 1904.[3] In a 1520 letter, Hernan Cortés wrote that the Aztecs raised and sold the little dogs as food.[4] Colonial records refer to small, nearly hairless dogs at the beginning of the 19th century, one of which claims 16th-century conquistadores found them plentiful in the region later known as Chihuahua.[5]