The Visigoths were a Germanic people united under the rule of a king and living within the Roman Empire during late antiquity. The Visigoths first appeared in the Balkans, as a Roman-allied barbarian military group united under the command of Alaric I. Their exact origins are believed to have been diverse but they probably included many descendants of the Thervingi who had moved into the Roman Empire beginning in 376 and had played a major role in defeating the Romans at the Battle of Adrianople in 378. Relations between the Romans and Alaric's Visigoths varied, with the two groups making treaties when convenient, and warring with one another when not. Under Alaric, the Visigoths invaded Italy and sacked Rome in August 410.