liturgy), which accompanied a spread of Eastern churches and monasteries that preserved and transmitted the Greek and Hellenistic tradition (the Cattolica monastery in Stilo is the most representative of these Byzantine monuments). From then to the Norman conquest of the 11th century, the south of the peninsula was constantly plunged into wars between the Byzantines, Lombardy, and the Aghlabid Dynasty. The latter established two Emirates in southern Italy: the Emirate of Sicily and, for 25 years, the Emirate of Bari. Amalfi, an independent republic from the 7th century until 1075, and to a lesser extent Gaeta, Molfetta and Trani, rivalled other Italian maritime republics in their domestic prosperity and maritime importance. From 999 to 1139, the Normans occupied all the Lombard and Byzantine possessions in Southern Italy, ending a millennium of imperial Roman rule in Italy, and eventually expelled the Muslims from Sicily. The Norman Kingdom of Sicily under Roger II was characterised by its competent governance, multi-ethnic nature and religious tolerance. Normans, Jews, Muslim Arabs, Byzantine Greeks, Lombards and "native" Sicilians lived in relative harmony. However, the Norman domination lasted only several decades before it formally ended in 1198 with the reign of Constance of Sicily, and was replaced by that of the Swabian Hohenstaufen dynasty, thanks to Constance's marriage to Henry VI, member of this family. In Sicily, King Frederick II endorsed a deep reform of the laws culminating with the promulgation of the Constitutions of Melfi (1231, also known as Liber Augustalis), a collection of laws for his realm that was remarkable for its time and was a source of inspiration for a long time after. It made the Kingdom of Sicily a centralised state and established the primacy of written law. With relatively small modifications, the Liber Augustalis remained the basis of Sicilian law until 1819. His royal court in Palermo, from around 1220 to his death, saw the first use of a literary form of an Italo-Romance language, Sicilian, that had a significant influence on what was to become the modern Italian language. During this period, he also built the Castel del Monte, and in 1224, he founded the University of Naples, now called, after him, Università Federico II. In 1266, conflict between the Hohenstaufen house and the Papacy led to Sicily's conquest by Charles I, Duke of Anjou. Opposition to French officialdom and taxation combined with incitement of rebellion by agents from the Byzantine