Susanne Mueller has a chapter in the recent Oxford Handbook of Kenyan Politics edited by Nic Cheeseman, Karuti Kanyinga, and Gabrielle Lynch on “High Stakes Ethnic Politics“.

Read it now for an accessible summary of the landscape with references for further study. From the Introduction:

This chapter examines the issue of ethnic politics: when it becomes important, why, and to what effect. The focus is on post-Independence Kenya, with reference to the colonial period and selected theoretical literature on ethnicity. I argue that ethnic politics is the by-product of historically weak institutions and political parties. When institutions are fragile and geography and ethnicity coincide, politicians generally woo their ethnic base with particularistic promises rather than policies. This is often self-reinforcing; the more winners and losers fall along ethnic lines, the greater the incentives for non-programmatic ethnic appeals. Accordingly, political trust weakens and ethnic divisions rise, sometimes inviting violence and reinforcing a vicious circle. Ethnic politics in Kenya is traceable to three critical junctures: first, to colonialism, which largely confined Africans to ethnic enclaves and prohibited national associations; second, to Independence in 1963, when the question of who gets what, when, and how became more salient as ethnically designed regions and districts battled for scarce national resources; and third to the return of multi-party politics in 1991, when politicians turned electoral contests for the executive into do-or-die events. Each of these junctures reinforced the personalization and regionalization of politics along ethnic lines. The result was non-programmatic political parties unable to make credible policy commitments to their constituents (Keefer  2008). This accompanied and promoted other important tendencies: weak institutions with only nominal checks and balances, political parties lacking policies and ideologies, and a strong centralized executive with a great deal of power to reward and sanction. Hence, ethnic groups either saw the presidency as their preserve or felt it was their turn to take power (Wrong  2009).