One of the reasons why their empire was so successful was that, unlike other ancient states, the empire welcomed outsiders. Foreigners could become Roman citizens. At first this was given as a reward for loyalty or for service in the Roman army, but under Emperor Caracalla, who ruled ad 211–217, citizenship was granted to
every free inhabitant of the empire. From the north of Britain to Egypts River Nile, everyone apart from slaves could now call themselves Romans.