There's a fair amount of research in economic history on almost exactly this topic. Two recent papers
http://www.nber.org/papers/w12328.pdf and
https://drive.google.com/file/d/0B4s_WKe-US99LV9XVTNVNzFxYW8... have looked at how measures of the artificial-ness of borders (how straight they are, how often they cut through the territory of ethnic groups, ratio of a country's area to the area of its convex hull) are correlated with various measures of welfare (e.g. GDP/capita, lack of conflict). The papers are often controversial because they often claim something approaching causality (see recent Twitter war
https://twitter.com/bill_easterly/status/753252113510268928).