Though you may come across a giant Chihuahua weighing in at, say, six pounds, more often than not, Chihuahuas range from two to five pounds. A good sized Yorkshire Terrier almost towers over a typical Chihuahua, weighing in at about seven pounds. In a Sumo Wrestling event, however, it would be hard to say who would win because the fiery Chihuahua would likely have some tricks up his sleeve. "Fiery" describes the personality of a Chihuahua and it also conjures up pictures of his homeland. He is a native of Mexico where he was bred for companionship and treated like royalty. His ancestry is very fuzzy with some followers claiming he actually comes from the Fennec Fox. The dainty little Yorkie was actually bred to catch rats in Northern England. He was a much bigger dog then. Now he is often seen in a celebrity's purse. There is another breed which stems from the Yorkshire Terrier called the Biewer Yorkie. This breed is essentially a Yorkie with piebald eyes.Both of these breeds are at risk for Small Dog Syndrome, a condition where the small dog thinks he is Alpha because his owner treats him like a child. It is easy to overpamper cute, little dogs but this can lead to restlessness and destructiveness in a Yorkshire Terrier and to aggressive behavior in Chihuahuas. Yorkies are considered good dogs for children but it is often best to monitor a Chihuahua with a child. Perhaps it's his heritage and the fact that he's been treated like royalty for hundreds of years but it can be tough to convince a Chihuahua that he can't do whatever he pleases. Early and consistent training, therefore, is imperative. The Yorkie is a very sweet dog but can become overprotective if you don't nip that behavior in the bud. Both breeds benefit from a moderate amount of exercise and it can be easy to forget how important exercise still is, even with such tiny canines.While Yorkies have a grounded, working class past, Chihuahuas come from more unusual beginnings. They were considered sacred to the Aztec and Toltec tribes of Mexico and their bones have been found buried with humans in Mexico. They were likely buried with their master when he died so they could accompany him to the other world. They were thought to cure asthma and were used as hot packs for aches and pains. While Chihuahua breeders tend to stay true to their ancient heritage, Yorkie breeders have tried crossing the breed with many other breeds, including the Maltese (Morkie), the Miniature Pinscher (Yorkie Pin), and the Poodle (Yorkie-Poo).Both of these breeds can be excellent companions, keeping in mind that, though Yorkies do well with families, Chihuahuas may do better in an adult household. Chihuahua lovers will tell you that they're affectionate, loving dogs while Yorkie owners love their dogs' gentle demeanor and playfulness. You might think of Yorkshire Pudding when you think of a Yorkie and, of course, Taco Bell when you think of a Chihuahua but both breeds are popular across cultures and both fit easily into a $3000 dog purse.