The Chihuahua is the smallest breed of dog in the world and is named after the state of Chihuahua in Mexico. Folklore and archeological finds show that the breed originated in Mexico. The most common theory and most likely is that Chihuahuas are descended from the Techichi, a companion dog favoured by the Toltecs and that the modern dog developed through breeding with miniaturised Chinese dogs brought to the Americas by the Spanish Conquistadors. (Source: Wikipedia)