Igbo-Ukwu (Igbo: Great Igbo) is a town in the Nigerian state of Anambra in the southeastern part of the country.

It is notable for three archaeological sites, where excavations have found bronze artifacts from a highly sophisticated bronze metal-working culture dating perhaps to the 9th or 10th century, centuries before other known bronzes of the region. The first, called Igbo Isaiah, was uncovered in 1938 by Isaiah Anozie a local villager, who stumbled upon the bronze works while digging beside his home. Subsequent excavations by Thurston Shaw in 1959 resulted in the discovery of two other sites, Igbo Richard and Igbo Jonah, containing the remains of an ancient culture. Artifacts have included jewelry, ceramics, a corpse adorned in what appears to be regalia, and many assorted bronze, copper, and iron objects. Some of these contain materials that are evidence of a long-distance trading system going to Egypt. Radiocarbon dating placed the sites around the 10th century or earlier, which would make the Igbo-Ukwu culture the earliest known examples of bronze casting in the region. The craftsmen were working centuries before those who made the more famous Ife bronzes.

In sociology and anthropology, an age grade or age class is a form of social organization based on age, within a series of such categories, through which individuals pass over the course of their lives.

This is in contrast to an age set, to which individuals remain permanently attached as the set itself becomes progressively more senior.

The number of age classes, the determining ages and the terminology vary significantly between traditions. Even within a single society, a person may belong to several overlapping grades in different spheres of life, e.g. per year a different school class and yet for several years on end a child, then an adolescent, finally an adult.

In tribal societies entry into an age grade - generally gender-separated - is often marked by an initiation rite, which may be the crowning of a long and complex preparation, sometimes in retreat. After a period of some years, during which they often perform certain common activities, alone or under senior guidance, members may be initiated either collectively or individually into a more senior age grade. This progression is often accompanied by the revelation of secret knowledge. In most cultures, age grade systems, as with age sets, are the preserve of men, and it is the older men who control a society's secret knowledge, collectively or restricted to a council of elders and/or specific positions such as shaman entrusted with the preparation of initiants.