Historiography is the study of the methodology of historians in developing history as an academic discipline, and by extension is any body of historical work on a particular subject. The historiography of a specific topic covers how historians have studied that topic using particular sources, techniques, and theoretical approaches. Scholars discuss historiography by topic — such as the "Historiography of the United Kingdom," the "Historiography of Canada," "Historiography of the British Empire", the "historiography of early Islam", the "historiography of China — and different approaches and genres, such as political history and social history. Beginning in the nineteenth century, with the ascent of academic history, there developed a body of historiographic literature. The extent to which historians are influenced by their own groups and loyalties — such as to their nation state — is a debated question.