First, the bit which confirms what you would expect (emphasis added)
Alesina and his coauthor show that geographic segmentation of ethnic groups is bad for the quality of government even after controlling for a nation’s overall fragmentation. Since poor government is responsible for the worst extremes of the human condition, regional segregation is a serious problem...They conjecture that segmentation bolsters destructive ethnic politics by making ethnic-specific policies easier to apply and ethnic voting blocs easier to organise.and one counter-intuitive result
Funny enough, religion doesn’t enter the mix. Religious segregation seemed to have no independent impact on government’s qualityThis is obviously the case not only for poor countries but also for wealthy ones, which is one reason why Singapore is paranoid about ethnic politics.
Apply the Copernican principle to India. Assume that it is not just this moment in time which is not special, but also this place, and the people who live here. Is there any reason to think these are a passing phase of India's history, or are we that different from Yugoslavia?