Naturalizing and excluding. Nationality and citizenship law in 19th and 20th century Germany. Nationality law in Germany came up as a legal institution of German federal states at the beginning of 19th century and underwent a process of nationalization. The principle of descent (Abstammungsprinzip), which was – before a legal reform in 2000 – hegemonic, was used to define German nationality primarily as a community of ethno-cultural descent. This restrictive use of German nationality law did not establish, however, a direct line of conceptual and political continuity between ‘ethno-cultural’ and ‘racial’ criteria, and it was primarily based on a politico-social constellation of political, demographic and national instability, not on a specific German national discourse.