The Nri kingdom, which is based in the town of Agukwu-Nri in modern-day Anambra state, is said to be the home of the oldest known monarchy in Nigeria. The Nri civilization, from which the kingdom sprung, is said to have its archaeological origins in the 10th century AD. The kingdom itself was not aggressive, but a peaceful domain ruled by a priest-king known as the "Eze Nri". Under the leadership of a chain of successful Eze Nri, the Nri civilization established itself as a premier cultural entity in the Niger River basin. Its envoys travelled extensive distances under the guise of medicine men and introduced elements of Nri culture to most of the communities in modern-day Delta, Anambra and Enugu states. Nri is credited with the establishment of the Ozo and Ikenga societies.