to a modern-day government census, as it was used by William to thoroughly document all the landholdings within the kingdom that could be properly taxed. 1086: the Battle of az-Zallaqah between the Almoravids and Castilians 1087: a new office at the Chinese international seaport of Quanzhou is established to handle and regulate taxes and tariffs on all mercantile transactions of foreign goods coming from Africa, Arabia, India, Sri Lanka, Persia, and South East Asia. 1087: the Italian cities of Genoa and Pisa engage in the African Mahdia campaign 1087: William II of England, son of William the Conqueror, is crowned king of England. 1088: the renowned polymath Chinese scientist and official Shen Kuo made the world's first reference to the magnetic compass in his book Dream Pool Essays, along with encyclopedic documentation and inquiry into scientific discoveries. 1088: The University of Bologna is established. 1088: Rebellion of 1088 against William II of England led by Odo of Bayeux. 1090–1100 1091: Normans from the Duchy of Normandy take control of Malta and surrounding islands. 1091: the Byzantine Empire under Alexios I Komnenos and his Cuman allies defeat Pechenegs at the Battle of Levounion 1093: Vikramaditya VI, ruler of the Western Chalukya Empire, defeats the army of Kulothunga Chola I in the Battle of Vengi. 1093: when the Chinese Empress Dowager Gao dies, the conservative faction that had followed Sima Guang is ousted from court, the liberal reforms of Wang Anshi reinstated, and Emperor Zhezong of Song halted all negotiations with the Tanguts of the Western Xia, resuming in armed conflict with them. 1093: the Kypchaks defeat princes of Kievan Rus at the Battle of the Stugna River 1093: Battle of Alnwick: Malcolm III of Scotland is killed by the forces of William II of England. 1094: the astronomical clock tower of Kaifeng, China—engineered by the official Su Song—is completed. 1094: El Cid, the great Spanish hero, conquers the Muslim city of Valencia 1094: a succession crisis following the reign of the Fatimid Caliph Ma'ad al-Mustansir Billah sparks a rebellion which leads to the split of Ismaili Shia into the new Nizari religious branch. 1095: Pope Urban II calls upon Western Europeans to take up the cross and reclaim the Holy Lands, officially commencing the First Crusade. c. 1095–1099: earliest extant manuscript of the Song of Roland 1096: University of Oxford in England holds its first lectures 1097: the Siege of Nicaea