Yoruba people viewed themselves as the inhabitants of a united empire, in contrast to the situation today, in which "Yoruba" is the cultural-linguistic designation for speakers of a language in the Niger–Congo family. The name comes from a Hausa word to refer to the Oyo Empire. The first Yoruba state was Ilé-Ifẹ̀, said to have been founded around 1000 CE by a supernatural figure, the first oni Oduduwa. Oduduwa's sons would be the founders of the different city-states of the Yoruba, and his daughters would become the mothers of the various Yoruba obas, or kings. Yoruba city-states were usually governed by an oba and an iwarefa, a council of chiefs who advised the oba. By the 18th century, the Yoruba city-states formed a loose confederation, with the oni of Ifẹ̀ as the head and Ifẹ̀ as the capital. As time went on, the individual city-states became more powerful, with their obas assuming more powerful spiritual positions and diluting the authority of the oni of Ifẹ̀. Rivalry became intense among the city-states. The Oyo state was conquered in 1550 by the kingdom of Nupe, which was in possession of cavalry, an important tactical advantage. As a result, Alafin Orompoto (), king of Oyo, was sent into exile. After returning, he built up an army based on heavily armed cavalry and long-service troops. This made them nearly invincible in combat on the northern grasslands and in the thinly wooded forests. By the end of the 16th century, Oyo had added to their domain the western region of the Niger, the hills of Togo, the Yoruba of Ketu, the Dahomey, and the Fon nation. A governing council served the empire, with clear executive divisions. Each acquired region was assigned a local administrator. Families served in king-making capacities. Oyo, as a northern Yoruba kingdom, served as a middle-man in the north–south trade and connected the eastern forest of Guinea with the western and central Sudan, the Sahara, and North Africa. The Yoruba manufactured cloth, ironware, and pottery, which were exchanged for salt, leather, and, most importantly, horses from the Sudan to maintain the cavalry. Oyo remained strong for two hundred years. It became a protectorate of Great Britain in 1888, before further fragmenting into warring factions. The Oyo state ceased to exist as any sort of power in 1896. Benin The Benin Empire was ruled by the Kwa-speaking Edo people, and by the mid-15th