Complex sentence: The Franks, Alemanni, and the Burgundians all ended up in northern Gaul while the Angles, Saxons, and Jutes settled in Britain, while the Vandals went on to cross the strait of Gibraltar after which they conquered the province of Africa.
Split into simpler sentences: The Franks, Alemanni, and the Burgundians all ended up in northern Gaul, and the Angles, Saxons, and Jutes settled in Britain. The Vandals went on to cross the strait of Gibraltar and then conquered the province of Africa.