Ethnic nationalism, also known as ethno-nationalism, is a form of nationalism wherein the nation is defined in terms of ethnicity.
The central theme of ethnic nationalists is that «nations are defined by a shared heritage, which usually includes a common language, a common faith, and a common ethnic ancestry». It also includes ideas of a culture shared between members of the group, and with their ancestors. However, it is different from a purely cultural definition of «the nation», which allows people to become members of a nation by cultural assimilation; and from a purely linguistic definition, according to which «the nation» consists of all speakers of a specific language.
Herodotus is the first who stated the main characteristics of ethnicity, with his famous account of what defines Greek identity. He lists kinship (Greek: ομόαιμον, homόaimon, «of the same blood»), language (Greek: ὁμόγλωσσον, homoglōsson, «speaking the same language»), cults and customs (Greek: ὁμότροπον, homόtropon, «of the same habits or life»).
The central political tenet of ethnic nationalism is that ethnic groups can be identified unambiguously, and that each such group 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, descent from a person of that nationality), and countries with strong traditions of civic nationalism tend to define nationality or citizenship by jus soli (the law of soil, 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 and cultural traditions, then, ethnic nationalism tends to emphasis narratives of common descent.
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 diaspora communities, at times using the term ethno nation or ethno nationalism to describe a conceptual collective of dispersed ethnics.