Another crucial fact established at the "Kouroukan Fouga" was the supremacy of Manden over all realms controlled by or allied to the federation including Wagadou and Mema. All future mansas would have to be chosen from the Keita clan, and the city-state of Niani (in present-day Guinea) would become the federal capital. Mansa Mari Djata returned to and rebuilt the capital of Niani, which had been destroyed by Soumaoro in his absence, and made it the most important center of trade in West Africa for the next 200 years.