In 1930, a cat named Wong Mau made its way from Burma to the United States with Dr. Joseph C. Thompson. This cat was deep brown in color and many fanciers thought she might be just a very dark Siamese. Dr. Thompson did not have this view, and he and other like-minded breeders decided to breed Wong Mau to determine just what breed she was. Wong Mau was the beginning of the Burmese breed.
Wong Mau's kittens appeared to prove Dr. Thompson's theory. When she was bred to a Siamese, the resulting kittens appeared to be Burmese/Siamese hybrids and pure Siamese. When the ones that looked like Burmese/Siamese hybrids were bred to each other, they produced the deep, dark Burmese kittens. The darker colored Burmese cats then bred true, showing that Wong Mau was, in fact, a hybrid of the Siamese and a dark-colored unknown cat.
Unfortunately, because this breed became so popular, hybrids began appearing in the show hall in 1947 instead of pure Burmese. Showing of hybrids was a violation of the show rules of the Cat Fanciers' Association and, for that violation, recognition of the Burmese was withdrawn. This recognition was not restored until 1953 when the Burmese Cat Society of America assured the registries that it would not happen again.