 Complete the following phrase:  The regions 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 