Ethnic nationalism is a form of nationalism wherein the "nation" is defined in terms of ethnicity. Whatever specific ethnicity is involved, ethnic nationalism always includes some element of descent from previous generations. It also includes ideas of a culture shared between members of the group, and with their ancestors, and usually a shared language; however it is different from purely cultural definitions of "the nation" (which allow people to become members of a nation by cultural assimilation) and a purely linguistic definitions (which see "the nation" as all speakers of a specific language).
The central political tenet of ethnic nationalism is that each ethnic group on earth is entitled to self-determination. The outcome of this right to self-determination may vary, from calls for self-regulated administrative bodies within an already-established society, to an autonomous entity separate from that society, to a sovereign state removed from that society. In international relations, it also leads to policies and movements for irredentism — to claim a common nation based upon ethnicity.
In scholarly literature, ethnic nationalism is usually contrasted with civic nationalism. Ethnic nationalism bases membership of the nation on descent or heredity - often articulated in terms of common blood or kinship - rather than on political membership. Hence, nation-states with strong traditions of ethnic nationalism tend to define nationality or citizenship by jus sanguinis (the law of blood - i.e. descent from a person of that nationality) while countries with strong traditions of civic nationalism tend to define nationality or citizenship by jus soli (the law of soil - i.e. birth within the nation-state). Ethnic nationalism is therefore seen as exclusive, while civic nationalism tends to be inclusive. Rather than allegiance to common civic ideals, then, ethnic nationalism tends to emphasise shared narratives and common culture. For example, Germany is often cited as an example of ethnic nationalism; German citizenship is open to "ethnic Germans" (e.g. descendents of Germans living in the former Soviet Union).
The theorist Anthony D. Smith uses the term 'ethnic nationalism' for non-Western concepts of nationalism as opposed to Western views of a nation defined by its geographical territory. Diaspora studies scholars extend this non-geographically bound concept of "nation" among diasporic communities, at times using the term ethnonation or ethnonationalism to describe a conceptual collective of dispersed ethnics.
A nation-state for the ethnic group derives political legitimacy from its status as homeland of that ethnic group, from its protective function against colonization, persecution or racism, and from its claim to facilitate the shared cultural and social life, which may not have been possible under the ethnic group's previous status as an ethnic minority.
Ethnic nationalism has sustained criticism because of its use by extremists to advocate racist agendas and genocide, such as the case of Nazi Germany and its extermination of millions of Jews and other ethnic and cultural groups during the Holocaust. More recent acts of violence that used ethnic nationalism as a justification include ethnic cleansing such as the Rwandan Genocide in 1994, the Srebrenica massacre in Bosnia and Herzegovina in 1995, and Operation Storm in Croatia in 1995.