The Efik are an Ibibio sub-group who migrated to the Cross River estuary in present-day Cross River State in the 16th–17th centuries from Uruan in Akwa Ibom. They founded the trading settlements known to Europeans as Old Calabar — Atakpa (Duke Town), Obutong (Old Town) and Mbiabo (Creek Town) — and from c.1650 onward dominated the slave and palm-oil export trade of the Cross River.
The Efik trading houses were named in pidgin English after the families that headed them — the Duke House, the Henshaw House, the Eyamba House, the Eyo Honesty House. They competed and intermarried; their merchants kept meticulous books, in some cases in literate English from the 18th century onward (the Diary of Antera Duke, written 1785–1788, is one of the earliest African-authored documents in English). They controlled access to the Aro middlemen and to the Ekoi and Efut hinterland.
The political institution above the houses was Ekpe (the leopard society) — a graded secret society whose senior members included the merchant elite. Ekpe enforced contracts, collected debts, regulated trade prices, punished offences, and could place a recalcitrant trader under interdict that suspended all dealings with him. Ekpe used the nsibidi system of ideographic signs to communicate sentences and decisions — one of the few indigenous writing systems of West Africa, paralleling Vai script of Liberia but very likely older. Nsibidi survives today on body art, ceremonial cloth and the carved gateposts of Ekpe lodges.
The Old Calabar slave trade was abolished formally by Britain in 1807 but persisted illicitly until the 1840s. Christian missions arrived in 1846 with the United Presbyterian Church of Scotland — Hope Waddell, William Anderson, and (most famously) Mary Slessor (1876–1915), who pioneered missionary medical work in the interior and campaigned against twin infanticide. The Niger Coast Protectorate was headquartered at Calabar from 1885 until 1906, when the capital moved to Lagos after amalgamation with Lagos Colony.
The Obong of Calabar — the head of the Efik kingdom — is today HRM Edidem Ekpo Okon Abasi Otu V. The Ekpe society continues as a cultural and fraternal institution in Calabar, southern Cameroon (where it is called Mgbe), and the Afro-Cuban diaspora (where it is the Abakuá society, founded in Havana c.1836 by enslaved Calabaris).