Which nation was the most powerful trade center in Eastern Africa?

Zimbabwe

The most powerful trade center in eastern Africa in the 1400s was Zimbabwe.

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would not cooperate with each other voluntarily.

pan-africanism or pan-africanism is a political, philosophical, cultural and social movement that promotes african twinning, the defense of the rights of african people and the unity of africa under a single sovereign state, for all africans, both africa as of the african diasporas.