response: Well the earliest evidence show that they were around in 100 AD, so as far as breeding I do not know
history: My parents just adopted a yappy little Chihuahua. Not so sure I'm stoked about the idea. I don't really know if they have any redeemable or interesting qualities, do you? Well, they descended from the Techichi, which was a favorite dog of the Toltec civilization in Mexico. Yeah, I imagined they would come from Mexico. I still don't understand why they're so small, though. Did they just get bred that way somehow?
knowledge: The earliest of these were found at Tres Zapotes in Veracruz, Mexico, which date to 100 AD, indirect evidence that the breed was in Mexico over 1400 years before the first Europeans arrived.