Complex sentence: Nevertheless, Agadja was unable to defeat the neighbouring kingdom of Oyo, Dahomey's chief rival in the slave trade, and in 1730, he became a tributary of Oyo.
Split into simpler sentences: Nevertheless, Agadja was unable to defeat the neighbouring kingdom of Oyo, Dahomey's chief rival in the slave trade. By 1730, he became a tributary of Oyo.