The historiography of precolonial Igbo society, that is, of Igboland before ca. 1900, relies on a variety of sources and methodologies: linguistic and archaeo-logical research, oral narratives and the products of their transformation into written accounts during the twentieth century, ethnographic and social anthropological studies (on political and kinship institutions, performances, and the arts), and a very limited number of written accounts by European visitors since the mid-nineteenth century.

Historical linguistics provides the earliest level of historical analysis. The Igbo language belongs to the Kwa subfamily of the larger Niger-Congo language family; glottochronology points to a point in time about 6,000 years ago when Igbo separated from proto-Kwa, assumed to be spoken in the Niger-Benue confluence area. Igbo has numerous dialects. Variations in spelling, grammar, or word use are common even among neighboring villages, creating a continuum of dialectical variation in Igboland that restricts mutual intelligibility among speakers of distant dialects. The Igbo literary standard developed since the late colonial period (see chapter 5) became only partially successful as a written vernacular; the Igbo educated elite continues to prefer English to written Igbo as means of communication even among itself. Within the large number of dialects—Pat Ndukwe (1992: 664) mentions estimates from 100 to 300, thereby indicating the uncertainty of classification—a smaller number of major dialect groups has been identified, but there is little agreement among Igbo linguists about them. The linguistic evidence, overall, points at diversity in Igboland.

Archaeology has provided information about the history of settlements, technology and trade. Neolithic farming communities settled in Igboland at least from 1000 BCE onward (Chikwendu 1992: 72–74). Early concentrations of population, with developed ceramic production, have been identified around Nsukka and Afikpo, but due to the sketchy evidence it remains unclear whether these were isolated centers or examples of a more general expansion of neolithic culture (Chikwendu 1992: 87–90). The famous archaeological finds at Igbo-Ukwu (Anambra State) showed that there was a society with an elaborate technology of metal (bronze) casting in the Anambra area by the tenth century CE (Shaw and University of Ibadan 1970; Shaw 1977). The analysis of the origin of beads and metal used in these and other finds showed long-standing long-distance trade connections between Igbo communities and areas further up the River Niger, extending to Gao and beyond (Insoll and Shaw 1997).