The American Longhair is the result of an experiment that went wrong. Breeders were trying to produce an American Shorthair with the shimmering coat and green eyes of a silver shaded Persian: instead they got the Persian in a shorter coat and leaner body. At first, it was proposed that these longhaired silver cats could be developed under the name "Silver Longhair", but more colors emerged and the American Longhair was born instead.
Similar crosses of Persian and British Shorthairs were also made, and other cats used in the development of the breed are known to have included the Burmese and even Russian Shorthairs, but once the longhaired coat had been achieved, these crosses were always bred back to Persian for coat length.