Ijo, people of the forests of the Niger River delta in Nigeria comprising a large number of formerly autonomous groups. They speak languages of the Ijoid branch of the Niger-Congo language family.
West of the main Niger outlets each group occupies a cluster of villages linked by loose ties of cooperation, mainly against outsiders. Its members claim descent from a common ancestor. At group and village levels government is by assemblies of elders, often presided over by priests. The economy is based on fishing, palm oil collecting, and floodland agriculture.
Formerly, when the economy was based primarily on fishing, each group claimed a distinctive culture and political autonomy. After contact with European merchants about 1500, however, the communities of Bonny, Calabar, and Nemke began trading first in slaves and then in palm oil. Wealthy traders became very powerful and governed in council with a hereditary king. Each trader purchased numerous slaves for incorporation into his own section of the community; if the trader had no suitable heir, an able slave succeeded him. Competition with other groups over hinterland markets and an emphasis on cultural separation rather than on links of common descent meant that ability was valued more than pedigree, permitting the emergence of such slave-born (i.e., non-Ijo) leaders as George of Calabar and Chief Jaja of Opobo.