The Chihuahua is such an old breed that its origin story is a bit murky. Historians agree that Chihuahuas originated in Mexico and are most likely descendents of the Techichi, a popular companion breed in the Toltec civilization. The Techichi can be dated back to at least the 9th century, but it is possible that drawings on pottery from Colimo dated back to 300 BCE may depict the breed. It is believed that once the Aztecs conquered the Toltecs during the 12th century, the Techichi was bred down to create the smaller Chihuahua. When the Spanish conquistadors conquered the Aztecs in the 16th century, Chihuahuas became more rare, mostly existing in small, remote villages. When the breed gained popularity in other countries during the 19th century, it earned its name after many of the dogs were found in the State of Chihuahua. The Chihuahua is the smallest breed of dog in the world.