The region's first known inhabitants, the Pictavi, a Gallic tribe, were conquered in 56 BC by the Romans, who then incorporated the area into Gaul as part of the province of Aquitania, with the Iberian Aquitani tribes. The Visigoths seized the region in 418 AD, but it passed to the Franks in 507. In 732 or 733, Charles Martel brought the Muslim invasion of Western Europe to a standstill by his victory in the Battle of Poitiers. From the 10th to the mid-12th century, the counts of Poitou were also the dukes of Aquitaine, and the city of Poitiers grew in importance.