Complex sentence: Initially the British involvement in Northern Nigeria was predominantly trade-related, and revolved around the expansion of the Royal Niger Company, whose interior territories spread north from about where the Niger River and Benue River joined at Lokoja.
Split into simpler sentences: Initially the British involvement in Northern Nigeria was predominantly trade-related and revolved around the expansion of the Royal Niger Company. The Royal Niger Company's interior territories spread north from about where the Niger River and Benue River joined at Lokoja.