Of related significance was his role in the development of Yoruba studies and writing. Studies on the reduction of Yoruba into writing have cited the works of British diplomats and traders such as George Robertson, Thomas Bowdich, Hugh Clapperton, and Richard Lander, who compiled lists of Yoruba words, numerals and place names between 1807 and 1830 and specifically the efforts by the Church Missionary Society in Sierra Leone to document and teach Yoruba after 1830. Osifekunde's work was more detailed. He also provided one of the earliest sources on the Owu war which triggered a political explosion in southern Yorubaland and identified reasons for the war, where it took place, the combatants, and impacts. He said the war began and was winding down before his enslavement in 1820, confirming Robin Law's thesis that the war was fought from $c .1817-1822 .{ }^{50} \mathrm{He}$ was right about the brotherhood of Ife and Ijebu kings, alluding to the military alliance between them during the wars and the longheld belief that the Yoruba descended from Ile-Ife. However, his point that Ijebu defeated and annexed Owu must have been second-hand information for him because Owu fell after he had been sold to the Americas. He probably heard this news from other enslaved Yorubas.  
Also, contrary to D'Avezac, that Osifekunde did not tell him about the location of Owu kingdom where many of the enslaved Yoruba embarked around 1820 originated, the memoir shows clearly that he did; but the writer,  
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[^0]:    50 Law, 1973, "The Owu war in Yoruba history," Journal of Historical Society of Nigeria, vol. 7, pp. 141-47.  
perhaps because of language difficulties, did not understand him. Perhaps Osifekunde disliked D'Avezac's method of asking the same question multiple times, implying the informant was lying. This is an illustration. On trade routes around Ijebu, Osifekunde mapped out a major route in southern Yorubaland: