Nri is the oldest documented kingdom of the Igbo and one of the most unusual political formations in African history: a hegemony exercised not by armies, taxes or territory but by ritual authority. Founded according to the Nri king list around 948 CE by Eri, said to have descended from the sky at the confluence of the Anambra and Niger rivers, the kingdom — Igbo Ukwu and Nri proper — produced the bronze regalia excavated at Igbo-Ukwu by Thurstan Shaw in 1959–1964 and radiocarbon-dated to the 9th–10th centuries: ceremonial vessels, pendants, sword hilts and a roped pot of breathtaking sophistication, executed in lost-wax casting using leaded bronze technology demonstrably independent of any North African or trans-Saharan source.
The Eze Nri was an ozo of ozos — installed only after the death of his predecessor through a long ritual cycle that included a symbolic death and burial. He was forbidden from shedding blood, from looking on a corpse, and from leaving the sacred precinct of Nri except on ritual journeys. Nri's instruments of power were the mbubu — ritual emissaries who travelled with elephant-tusk staffs across hundreds of Igbo villages to cleanse abominations (nso ala), arbitrate disputes, and ordain new ozo titleholders. Communities that received the mbubu were bound by Nri ritual prohibitions; those that violated them were placed under interdict.
Nri controlled no army, levied no tribute and conquered no territory. Its influence covered the Igbo heartland — present-day Anambra, parts of Enugu, Imo and Abia states — and reached the Igala kingdom to the north and the Aro to the south-east. Nri also enforced the absolute prohibition on the sale of Igbo as slaves: the kingdom's ritual interdict on enslavement of free-born Igbo by Igbo is one reason the trans-Atlantic slave trade in the hinterland was channelled through middlemen — particularly the Aro Confederacy — rather than directly through Nri.
The Anglo-Aro Expedition of 1901–02 destroyed the Aro Long Juju at Arochukwu, and the Anglo-Nri operation of 1911 forced Eze Nri Òbalíke to renounce the ritual prohibitions and submit to British indirect rule. The Eze-ship was vacant for several decades. Eze Nri Òbidiegwu Onyesoh was installed in 1988, restoring the line. The Nri kingdom is today recognised by Anambra State as the ritual head of Igbo civilisation, and Igbo-Ukwu is on the UNESCO World Heritage tentative list.