Ethnicity can be defined as social identification based upon the presumption of shared history and common cultural inheritance. Such identities play a prominent role in political struggle in the modern world. Whether the object of struggle is securing resources in competition with other ethnic groups or resisting the dominance of an encroaching state, ethnic identity provides a powerful ideology for political mobilization. The ethnic groups engaged in these struggles often cut across class lines, containing both elites who provide group leadership and a mass of members drawn from lower classes. Thus, in the modern world, ethnicity is frequently bound up with factional competition and political change.

Did ethnicity play an important role in political struggle before the emergence of the modern world? Early approaches to ethnicity suggested that it did not. From the mid-1930s to the mid-1960s, ethnic groups were regarded as primordial human groups, arising from cultural isolation and persisting by habit and custom. Competition between ethnic groups was regarded as a recent phenomenon, created during the process of modernization as diverse tribal groups were brought together in overarching states. Some observers expected ethnic conflict within these “plural societies” to be a temporary phenomenon; conflict was expected to disappear in the course of modernization as national institutions matured (e.g., Apter 1967). Others, more pessimistic, pointed to forces that would perpetuate ethnic identity and conflict: either the deep-seated, enduring character of ethnic loyalties (Geertz 1963) or the determination of colonial and neocolonial elites to maintain ethnic stratification systems (Furnivall 1939).