Onitsha Mmili was known as Ado N’Idu, it was founded by one of the sons of Chima, the founder of Issele-Uku kingdom in western Igboland. Chima, a prince of the ancient Benin kingdom emigrated, settled and founded what is now known as Issele-Uku in Aniocha North Local Government Area. The eldest son of Chima eventually emigrated across the Niger River to establish the Onitsha community. It is a town in South East Nigeria famed for its commerce, education and religious centre that lies beside the Niger.

Onitsha is the largest markets in West Africa, a center point where billions of naira are transacted every day.

Onitsha operates a traditional government headed by the Obi, the titular head of the town who is assisted by Ndi Ichie, titled red cap elders or chiefs. Among these are Ndi Ichie Ume, who are the First Class Chiefs. The Ndi Ichie are classified into six, namely: Onowu Iyasele, Ajie Ukadiugwu, Odu Osodi, Onya Ozoma, Ogene Onira and Owelle Osowa, with Onowu Iyasele as the traditional Prime Minister. There are also other Ndi Ichie, who are ranked second class, known as Ndi Okwa and third class, known as Ndi Ichie Okwareze. The Ndi Ichie serve as Council of Advisers to the Obi who solicits their advice in major decisions he takes in the Kingdom.

When the ruling Obi joins his ancestors, the Onowu Iyasele takes charge until a new Obi is enthroned.

Once a year in October the kingdom of Onitsha holds the Ofala Festival which coincides with the traditional New Yam festival held in many parts of Igboland. It is a way for the people of Onitsha to keep their culture alive and it has become a major event that draws visitors from far and wide to the city.

There are nine groups of Kindred, (Ebo Etenani), making up Onitsha Ado Community.

Onitsha traditionally consists of nine villages, otherwise known as Ebo Itenani. These are descendants of the progenitor Umuezechima comprising Isiokwe, Olosi, Umuezearoli, Okebunabo, Obikporo and Ogbeotu which claim origin from Igala in Kogi state, Awada (Ogbeozoma), Obamkpa comprising Umuasele, Iyiawu and Odoje Ndugbe and Odumegwu Gbuagu, Ubulu na Ikem, Ulutu, Ubene, Ogboli Eke, Obior and Ogbeotu. Within these groupings there are six administrative wards namely Okebunabo, Umuezearoli, Ogbeolu, Isiokwe na Ogboli Olosi, Obamkpa and Eke na Ubene.

The history of Onitsha began with the migration of its people from the Benin Empire towards the end of early part of the Sixteenth Century AD. The migration was as a result of a wave of unrest, war and displacement unleashed by the Islamic movement from North Africa.

It was during their passage through the outskirts of Ile-Ife that they acquired the name Onitsha – a corruption of the Yoruba word Orisha and Udo, the famous shrine worshipped by the people. As time went on, the combination of the two words, Onitsha for Orisha and Ado for Udo culminated in the present name , Onitsha Ado.

The people of Onitsha left the outskirts of Ile-Ife and resettled in the Benin Kingdom and soon established themselves as one of the clans in the Benin Kingdom exercising all the rights and privileges attached thereon.

As a result of a long process of acculturation in Benin, the Onitsha people jealously guarded their acquired rights particularly with regard to their revered Shrine Udo.

It was suggested that the reason why the Onitsha people quarreled with Oba Esigie, (1404-1550), of Benin was because of the slight, the Oba gave their shrine-Udo. It was customary for newly installed Oba to pay homage to all important Shrines in the Benin Kingdom by slaughtering a cow in the shrines enclave. Oba Esigie failed to do this at the Onitsha people’s Udo-Shrine, hence the quarrel.

It took the Onitsha people several years before they got to Obior and Ilah and finally crossed the River Niger and established Onitsha Ado. They stopped at several places in the then Mid-West now called Delta State, places like Agbor, Issele-Uku, etc. This explains the affinity with the inhabitants of Delta State like Ilah, Issele-Uku, Obbaamkpa, Onitsha-Olona, Onitsha Ugbo, Agbo, Obior, Onitsha Ukwu and so on.

After their arrival on the east bank (Onicha-mmili, “Onitsha-on-water”), the community gradually became a unitary kingdom, evolving from a loosely organized group of “royal” villages to encompass “non-royal” villages comprising Igala settlers, and the native Igbos to form a more centralized entity.

Eze Aroli was apparently the first genuinely powerful Obi of Onitsha, the ruler of the city.

Onitsha slowly grew to become an important trading port for the Royal Niger Company in the mid-1850s following the abolition of slavery and with the development of the steam engine when Europeans were able to move into the hinterland.

Trade in palm kernels, palm oil, and other cash crops on the coast of Bight of Biafra increased around this river port in the 19th century.

In 1857 British palm oil traders established a permanent station in the city with Christian missionaries joining them, headed by the liberated African bishop Samuel Ajayi Crowther (a Yoruba receptive) and Reverend John Taylor (an Igbo Recaptive).

In 1900 Onitsha became part of a British protectorate.The British colonial government and Christian missionaries penetrated most of Igboland to set up their administration, schools and churches through the river port at Onitsha.

Dennis Memorial Grammar School established by the Anglican Church Mission Society in 1925
More immigrants from the hinterland of Igboland were drawn to the emerging boom town as did the British traders who settled there in Onitsha, and coordinated the palm oil and cash crops trade.

In 1965, the Niger River Bridge was built across the Niger River to replace the ferry crossing. This has helped to grow trade routes with western Nigeria and created significant economic linkages between Onitsha and Benin City and Lagos particularly.