Answer: The city states include Great Zimbabwe, Mogadishu,Mombasa, Zanzibar, Kilwa.
They were successful because they are connected to the Indian ocean trade network.
Explanation: The Indian ocean trade network is a trade network involving the Southeast Asia countries, India,Arabia, and East Africa,it is a vast interconnected trade network involving importing and exporting of goods long before the Europeans discovered the Indian ocean. During the early stages of this trade network several items were traded like SILK from China,Percian JEWELS,Roman COINS, this trades led to the growth of those City states in East Africa. Religious beliefs and ideologies were also shared like Buddhism,Jainism etc mainly by Indians converting some Southeast Asians.
