Pre-1500 — Ancient settlement#
Egba, Egbado (Yewa), Ijebu, Awori, Remo and Anago Yoruba settle the Ogun River basin.
1500 — 1804 — Pre-colonial polities#
The Ijebu Kingdom at Ijebu-Ode is among the oldest Yoruba kingdoms (Awujale dynasty, claimed from c. 1430). Egba towns (Iberekodo, Igbein) are scattered under Oyo overlordship.
1804 — 1903 — The long 19th century#
The collapse of Old Oyo (c. 1835) sends Egba refugees south under Sodeke, who founds Abeokuta (1830) at the Olumo Rock. Abeokuta successfully defends itself against Dahomey at the Battle of Owiwi (1832) and the famous Battle of Abeokuta (3 Mar 1851) — repelling King Ghezo. Ijebu's monopoly on inland trade to Lagos provokes the Ijebu Expedition of 17–22 May 1892 under Major Carter and Colonel Norman Scott: the Battle of Yemoji (20 May 1892) breaks Ijebu power and opens the Yoruba interior. Egba United Government (1898–1914) is the only Yoruba polity to keep treaty-recognised internal autonomy until 1914, when Lugard abolishes it after the Adubi (Ijemo) Rising of 1918.
1900 — 1960 — Colonial provinces#
Abeokuta Province; Ijebu Province. The 1947 Abeokuta Women's Revolt led by Funmilayo Ransome-Kuti against the *Alake* Ademola II forces his abdication (29 July 1949).
1960 — present — State creation chain#
- 1967 — Western State (capital Ibadan).
- 3 Feb 1976 — Murtala creates Ogun State (capital Abeokuta).