Thursday, we took a fantastic bus tour of Northern Ireland. Amidst the awe-inspiring natural scenery and the seemingly cheerful towns, it was very easy to forget the magnitude of violence and strife that occurred there just a couple of decades ago. Our tour guide, Mac, described to us in detail the atrocities committed between unionists and nationalists in the adorable towns we passed. As we drove into Belfast, a seemingly peaceful city, he told us about the horrors experienced by a friend of his from university who spent his young adult life in jail after “getting caught up in that mess.” And as we soaked in the beauty of the Northern Irish coast, he told us how Protestants and Catholics, two sects of the same religion, two sides of the same coin, brutally murdered one another for years.

But is that really a surprise? The situation is similar between Sunni and Shi’a Muslims throughout the Middle East. Whether within states or between them, the differences between the two sects of Islam have caused significant bloodshed and countless abuses of human rights, all in the name of ideology, in the name of defending “us” against “the others.”

Sectarian violence seems like a foreign concept, something far away and barbaric that we Americans will never have to deal with, but conflict between groups has colored both world and American history. The American Civil War, a war of brother against brother, was fought between loyalists and separatists as well. The Civil Rights movement brought to light the brutal discrimination and violence within America against minority races. Just the day before we learned about The Troubles, a white man in Charleston, South Carolina chose to take the lives of nine black Americans in their place of worship. There is sectarian violence in America today. Not just across the globe in a developing country I may never visit. Not just amongst foreign people I will never meet. Three hundred miles from my hometown there is sectarian violence amongst citizens of my country.

The consequences of the natural human inclination to divide ourselves up are enormous in international politics, especially for the European Union. Though the EU presents an image to the world of peace and stability, the fact is that The Troubles occurred between groups within Ireland and the United Kingdom, two EU member states and close neighbors. If the relationship between the Irish and the Northern Irish, two Gaelic, English speaking peoples who have shared a small island for centuries has such a complex and bloody history, the future of Europe will likely be even more complex. While overcoming the rationalist challenges to European integration like states’ desire to defend sovereignty and the logistic and economic challenges associated with coordination are no small feat, looking at the history of even some of the most peaceful and developed areas of the world suggests that identity barriers and thinking of those different from us as the enemy may be even more difficult.