for Italy, though it was generally dominated by non-Italian interests. The separation with the Eastern world continued to increase. Leo III was the first Pope to date his Bulls from the year of Charlemagne's reign (795) instead of those of Byzantine emperors. This process of isolation from the Eastern Empire and connection with the Western world of France and Germany, which had started three centuries before, was completed at the beginning of the 9th centuries. Sicily, Calabria, Puglia and Venice were the main exceptions to this rule. After the death of Charlemagne (814) the new empire soon disintegrated under his weak successors. The equilibrium created through the great emperor's charisma fell apart. This crisis was due also to the emergence of external forces, including the Saracen attacks and the rising power of the marine republics. Charlemagne had announced his division of the Empire in 806: the Lombard-Frank reign, together with Bavaria and Alamannia, was to be handed over to his son Pepin of Italy. After Charlemagne's son Louis the Pious died in 840, the treaty of Verdun in 843 divided the empire. Louis' eldest surviving son Lothair I became Emperor and ruler of the Central Franks. His three sons in turn divided this kingdom between them, and Northern Italy became the Kingdom of Italy under Louis II, Holy Roman Emperor in 839. The first half of the 9th century saw other troubles for Italy as well. In 827, Muslim Arabs known as Aghlabids invaded and conquered Sicily; their descendants, the Kalbids, ruled the island until 1053. In 846, Muslim Arabs invaded Rome, looted St. Peter's Basilica, and stole all the gold and silver in it. In response, Pope Leo IV started building the Leonine walls of the Vatican City in 847; they were completed in 853. In the late 9th century, the Byzantines and the Franks launched a joint offensive against the Arabs in southern Italy. Southern Italy With Charlemagne's conquest of 774, the north of Italy was politically separated from the south completely. Though the Byzantines had continued to hold most of Apulia and Calabria and the Lombard duchies of the south had been aloof of Pavian policies for a century, the situation was exacerbated by the loss of a centralising Lombard authority in the north. Creation of independent moieties (774–849) Under Arechis II of Benevento and his successors, it was the Beneventan policy to pay homage to the