In 1951, Tibet was annexed by China and incorporated into the communist People's Republic. Through a historiographical examination, the author demonstrates how Tibetan society evolved culturally, politically, and religiously from the 7th to the 20th century, and which historical factors ultimately contributed to the invasion by China. It is explained how Beijing legitimizes the annexation, which is always referred to as a "peaceful liberation," and how this argument is challenged by critics. Finally, the social system of the country is analyzed in terms of Luhmann's systems theory to determine what form of state and societal model can be associated with traditional Tibet.