Despite the long time of separation, dating about six thousand years ago, the Ijo (central, western and eastern) maintained a common language and culture. They are linguistically related to their neighbours, such as the Edo, Igbo and Yoruba, all grouped under the Niger-Kordofanian proto-phylum of languages. As a result of the referrals to these people by eminent historians as „city-states‟ and „trading states‟ made it imperative for this study to painstakingly review the traditional economic system of the Ijo, especially of the Eastern Niger Delta states. This entailed a survey of their land and tenure system, agricultural products and practices, crafts and manufacturing, and trade and marketing in the pre-Atlantic trade period. Having considered the primordial socio-political and economic institutions in Ijoland, the impact of the transAtlantic trade nexus the transformations it wrought on the Ijo society, the economic impact of the Atlantic trade: its attendant accumulation of wealth, therefore power, the specifications and specializations in the political apparatuses, and the eventual move away from the village assemblies of the various Ijo states to the centrality of the political institutions as evidenced in the case of the Elem Kalabari, and of course in the other city-states were equally surveyed in detail. The paper in which the analytical method was extensively used concluded that the socio-political institutions of the Ijo (Izon) which attained higher degrees of centrality were already in existence before the Atlantic slave trade (although it aided the development of the War Canoes and City-States) and colonial times.