A mastiff is a breed of large working dog used as a guard and fighting dog in England for more than 2,000 years. Dogs of this type are found in European and Asian records dating back to 3000 BC. Sometimes called the Molossian breeds for a common ancestor, numerous large, heavily built dog breeds incorporate the name mastiff. They often function as war dogs or guardians. The Roman invaders of England sent the English mastiff to compete in the arenas of ancient Rome, where the dog was pitted against bears, lions, tigers, bulls, other dogs, and human gladiators. The breed also fought in the later bullbaiting and bearbaiting rings of England.