large expeditions that reached the eastern Mediterranean1096–1099, 1147–1149, 1189–1192, 1217–1229 and 1248–1254. In 1820 Charles Mills counted nine distinct crusades. Numbering conventions are retained, mainly for convenience and tradition, but are somewhat arbitrary systems for what some historians now consider to be seven major and numerous lesser campaigns. The crusades to the Holy Land provided a template for other campaigns conducted in the interest of the Latin Church: The Spanish Christian kingdoms overcame Muslim Al-Andalus in the 12th and 13thcentury; Between the 12th to 15thcentury German expansion into the pagan Baltic region; Non-conformity was suppressed, particularly in Languedoc during what has become called the Albigensian Crusade; The assertion of Papal temporal ambitions in Italy and Germany that are now known as political crusades. In addition the 13th and 14th centuries saw unsanctioned, but related popular uprisings to recover Jerusalem known variously as Shepherds' or Children's crusades. Studies of primary sources In 1841, German historian Heinrich von Sybel published his History of the Crusades, a critical study of then-current Western sources. This initiated a series of similar works, such as those published by Heinrich Hagenmeyer between 1877 and 1913. As a result, the Western texts edited for the series have now been supplanted by superior editions. Documentary sources include charters, diplomas, letters, privileges, and similar texts. Charters recording legal transactions such as sale or gift of property, or concession of rights are the most common documentary source from the Middle Ages. A sizeable number remain that were issued by crusaders. These include records of fund-raising transactions and pious donations. As such they inform historians on the financing of crusades, the motivations, and states of mind as well as family crusading traditions. They are of fundamental importance in the study of Crusading in the Outremer, Greece, and the Baltic region. Particularly the collections of charters related to military orders and ecclesiastical institutions. Although many letter do not survive, they are referred to in the narrative sources. Correspondence includes diplomatic and private missives, papal bulls proclaiming and regulating crusades including the crusaders' spiritual and temporal privileges and appeals for military assistance. Examples of treaties and contracts such as the 1190 treaty of Adrianople between Frederick Barbarossa and Byzantium during the Third Crusade, the Treaty of Venice and the Treaty of Christburg provide information on the organisation and outcomes of many crusades. In addition, historians utilise sermons, law codes, genealogies, financial records, the rules