The earliest of these were found at Tres Zapotes in Veracruz, Mexico, which date to 100 AD, although most artifacts relating to its existence are found around Mexico City.It has been argued that these pots arrived with survivors from the Casas Grandes site in Chihuahua, Mexico, after it was attacked and destroyed around 1340 AD.Unlike many longhaired breeds, longhaired Chihuahuas require no trimming and minimal grooming.
No records of the Techichi are available prior to the 9th century, although dog pots from Colima, Mexico, buried as part of the western Mexico shaft tomb tradition which date back to 300 BC are thought to depict Techichis.
However, in May 2008, the Chihuahua Club of America voted that merles would not be disqualified in the United States, and would be fully registrable and able to compete in American Kennel Club (AKC) events.
Opponents of merle recognition suspect the coloration came about by modern crossbreeding with other dogs and not via natural genetic drift.
Dogs of either coat type may be identified as either "apple head" or "deer head" Chihuahuas, particularly in the United States.
Apple heads have rounded heads, close-set eyes, and relatively short ears and legs.