In 732 or 737—modern scholars have debated over the date—Charles marched against an Arab-berber army between Poitiers and Tours and defeated it in a watershed battle that turned back the tide of the Arab-berber advance north of the Pyrenees. But Charles's real interests lay in the northeast, primarily with the Saxons, from whom he had to extort the tribute which for centuries they had paid to the Merovingians.