The categories Hutu and Tutsi have an origin in pre-colonial Rwanda. However, with the arrival of the Germans in about 1900, and particularly after the arrival of the Belgians in 1920, the categories began to "rigidify" and become thought of as ethnic. The modern history of Rwanda has in many ways been one of tension between the majority Hutu and minority Tutsi "ethnic" groups. While there has been much scholarship about the emergence of these separate ethnic identities, particularly though the colonial governance structures, before and after independence in 1961, people within Rwanda acted within the parameters of the Tutsi-Hutu division. Regardless of the historical validity of the division, Rwandans in the late 20th century acted as if they were real.