This background paper examines how conflict affects horizontal inequality. While a large literature looks at how horizontal inequality is linked to the onset of armed conflict, we know very little about if, and how, conflict in turn affects such inequality. We argue that there are good reasons to believe that armed conflict should exacerbate levels of horizontal inequality, and that this dynamic in turn has the potential to create an inequality-conflict trap akin to the already established economic conflict trap. We examine all intrastate conflicts in 120 countries, for the 1989 to 2018 period, drawing on measures of inequalities between regions as a proxy for horizontal inequality. We find that lowintensity conflicts are not systematically linked to levels of horizontal inequality. High-intensity conflicts, i.e., conflicts that incur more than 1,000 battle deaths and last for more than five years, in contrast are associated with substantially higher levels of horizontal inequality in the post-conflict phase. This pattern endures for many years after the conflict has ended. Combined with previous research demonstrating that horizontal inequality may induce armed conflict, our paper provides suggestive evidence consistent with the notion of an inequality-conflict trap.