While the Nigerian Civil War devastated Igbo business activities across Nigeria, and precipitated a mass return of Igbo migrants to their home area, it also laid the foundation for a consolidation and rapid development of Igbo informal enterprise, which has had integrative rather than divisive social and economic consequences for Nigeria as a whole. Operating below the radar of political competition, the demands of informal enterprise development have nurtured strong inter-ethnic and inter-regional links between the Igbo, Hausaa, Yoruba and other Nigerian as well as non-Nigerian groups. With a particular focus on Igbo informal manufacturing, long-distance trading networks and informal money changing, this paper will consider the role of the informal economy in the development of popular structures of national unity. It will also show that these processes of economic integration from below have increasingly been strained by political struggles from above, creating a tide of violence and ethnic polarization that, even more than the Civil War, threatens to unravel the underlying social fabric of Nigerian nationhood.
That is from the abstract of a paper by Kate Meagher of the Development Studies Institute, London School of Economics. The full pdf file, ungated, is here.