This thesis is concerned with the relationship between Regional Inequalities (RIs) and conflict occurrence. While its starting point is the theory of Horizontal Inequalities (HIs) based on the use of ethnic groups as the units of analyses, this thesis argues that the RIs approach that uses regions as the units of analyses has several advantages: It simplifies the process of identifying the units using regions that are often official geographical areas and administrative entities; it simplifies the data-gathering process as regional data is often available; and it increases the practical relevance of the research, as the inequalities are easier to address because regions often have or can be granted some sort of political and economic autonomy. This thesis then tests the theory of RIs on three cases from Sudan: The first and second civil war between the North and the South; the rebellion in Darfur; and the civil strife in East Sudan. From a theoretical point of view, it finds that the complexity and flexibility of ethnic groups in Sudan renders them inadequate for analytical purposes, and that regional, not ethnic, identity is the dominant form of identity relevant for the conflicts in the Sudanese cases. This thesis identifies multidimensional RIs in the Sudanese cases and strong correlation between regional inequalities and conflict occurrence in Sudan. The inequalities are multidimensional and persistent, and conflicts in the three cases have occurred or been intensified when there has been a widening of inequalities.