The Chihuahua is the world's smallest breed. The dog's origins are still a mystery. Experts predict that it arrived in the Americas with the Spanish armies of Hernando Corte in 1519. Although other say that is comes from the Techichi, a dog bred by the Toltecs of Mexico as early as the ninth century. The dog's name is from the Mexican state Chihuahua. The most valued dog weighs under 2 ¼ lb (1.3 kg)