Despite some video quality troubles and a few errors, this short lecture by Paul Lovejoy is well worth the listen. Oyo was a northern Yoruba state with a cavalry and links to the Nupe, Bariba and Hausaland. Ali Eisami was also enslaved in Oyo so the state was connected to Borno via trade and the slave trade. I just wish we had more sources on the history of this fascinating Yoruba empire. Robin Law's monograph endeavored to make do with the fragmentary oral traditions, limited external sources and later Yoruba histories of the post-imperial Oyo years. What he accomplished was quite impressive for reconstructing the political, economic, social, and administrative features of Oyo, but it all seems so speculative.