Ibadan area becomes a British Protectorate after a treaty signed by Fijabi, the Baale of Ibadan with the British acting Governor of Lagos, George C. Denton.

Lagos Colony was a British colonial possession centred on the port of Lagos in what is now southern Nigeria. Lagos was annexed on 6 August 1861 under the threat of force by Commander Beddingfield of HMS Prometheus who was accompanied by the Acting British Consul, William McCoskry. Oba Dosunmu of Lagos (spelled "Docemo" in British documents) resisted the cession for 11 days while facing the threat of violence on Lagos and its people, but capitulated and signed the Lagos Treaty of Cession. Lagos was declared a colony on 5 March 1862.

By 1872, Lagos was a cosmopolitan trading center with a population over 60,000.

In the aftermath of prolonged wars between the mainland Yoruba states, the colony established a protectorate over most of Yorubaland between 1890 and 1897. The protectorate was incorporated into the new Southern Nigeria Protectorate in February 1906, and Lagos became the capital of the Protectorate of Nigeria in January 1914.

Since then, Lagos has grown to become the largest city in West Africa, with an estimated metropolitan population of over 9,000,000 as of 2011.

Ibadan (UK: , US: ; Yoruba: Ìbàdàn) is the capital and most populous city of Oyo State, in Nigeria. It is the third-largest city by population in Nigeria after Lagos and Kano, with a total population of 3,649,000 as of 2021, and over 6 million people within its metropolitan area. It is the country's largest city by geographical area. At the time of Nigeria's independence in 1960, Ibadan was the largest and most populous city in the country, and the second most populous in Africa behind Cairo.

Ibadan is located in south-western Nigeria, 128 kilometres (80 mi) inland northeast of Lagos and 530 kilometres (330 mi) southwest of Abuja, the federal capital. It is a prominent transit point between the coastal region and areas in the hinterland of the country. Ibadan had been the administrative centre of the old Western Region since the early days of British colonial rule, and parts of the city's ancient protective walls still stand to this day. The principal inhabitants of the city are the Yoruba people, as well as various communities (notably Igbo, Hausa, and Efik) from other parts of the country.