Weber however maintained that ethnic groups were "künstlich" (artificial, i.e. a social construct)
because they were based on a subjective belief in shared "Gemeinschaft". Secondly, this belief in shared Gemeinschaft did not create the group; the group created the belief. Third, group formation resulted from the drive to monopolise power and status. This was contrary to the prevailing naturalist belief of the time, which held that socio-cultural and behavioral differences between peoples stemmed from inherited traits and tendencies derived from common descent, then called "race".
Another influential theoretician of ethnicity was Fredrik Barth, whose "Ethnic Groups and Boundaries" from 1969 has been described as instrumental in spreading the usage of the term in social studies in the 1980s and 1990s.  Barth went further than Weber in stressing the constructed nature of ethnicity.
To Barth Ethnicity was perpetually negotiated and renegotiated by both external ascription and internal self-identification. Barth's view is that ethnic groups are not discontinuous cultural isolates, or logical a prioris to which people naturally belong. He wanted to part with anthropological notions of cultures as bounded entities, and ethnicity as primordialist bonds, replacing it with a focus on the interface between groups. Ethnic Groups and Boundaries, therefore, is a focus on the interconnectedness of ethnic identities. Barth writes: "[...] categorical ethnic distinctions do not depend on an absence of mobility, contact and information, but do entail social processes of exclusion and incorporation whereby discrete categories are maintained despite changing participation and membership in the course of individual life histories."
In 1978 anthropologist Ronald Cohen claimed that the identification of "ethnic groups" in the usage of social scientists often reflected inaccurate labels more than indigenous realities:
... the named ethnic identities we accept, often unthinkingly, as basic givens in the literature are often arbitrarily, or even worse inaccurately, imposed.