Final answer:
The empires and Kingdom of western Sudan were structured by trade and commerce, religion and cultural unity, military conquests, and political alliances, with trade being a key factor.
Step-by-step explanation:
The structure of the empires and Kingdom of the western Sudan was promoted by various factors including trade and commerce, religion and cultural unity, military conquests, and political alliances. Trade, particularly in gold, salt and slaves, was a unifying element, as it fostered economic growth and encouraged networks of exchange between various regions. The spread of Islam, which began after the Arab invasion, served to unite people under a common religion and set of practices. The Bantu migration also spread related languages and cultural practices across the continent.
Military prowess allowed the states on the savanna to exert their influence and control over others, often leading to the creation of powerful empires through conquest. Diplomacy later became the norm, with defeated states becoming tribute bearers rather than territories being overtly fought over. Political alliances were forged to maintain peace and ensure mutual prosperity. All these elements were crucial in shaping the grand empires of the western Sudan, defining their socio-economic and political landscapes.