Following Alboin's victory over the Gepids, he led his people to Italy, which had become severely depopulated and devastated after the long Gothic War (535–554) between the Byzantine Empire and the Ostrogothic Kingdom. The Lombards were joined by numerous Saxons, Heruls, Gepids, Bulgars, Thuringians and Ostrogoths, and their invasion of Italy was almost unopposed. By late 569, they had conquered all of northern Italy and the principal cities north of the Po River, except Pavia, which fell in 572. At the same time, they occupied areas in central and southern Italy. They established a Lombard Kingdom in north and central Italy, later named "Regnum Italicum" ("Kingdom of Italy"), which reached its zenith under the 8th-century ruler Liutprand. In 774, the kingdom was conquered by the Frankish king Charlemagne and integrated into the Frankish Empire. However, Lombard nobles continued to rule southern parts of the Italian peninsula well into the 11th century, when they were conquered by the Normans and added to the County of Sicily. In this period, the southern part of Italy still under Lombard domination was known to the foreigners by the name Langbarðaland (Land of the Lombards), as inscribed in the Norse runestones. Their legacy is also apparent in the name of the region of Lombardy in northern Italy.