The history of Mastiff is very interesting. This is one of the most ancient dog breeds. “Mollosus” was the ancestor of modern Mastiff. Mollosus was a typical ferocious guard dogs mentioned in the old Egyptian, Greek and Babylonian history. The dog is believed to have lived 5000 years ago. The modern Mastiff is bred in England where guard dogs were in high demand during the medieval period to protect their houses and wealth.