Every country is built on the bodies of the people who inhabited it beforehand, since all the way back when homo sapiens killed off the other hominids in Europe and Africa. There are very few places that haven't conquered by a new wave of immigrants who massacred or enslaved the natives at one point or another. The past is a litany of sorrows and once you start feeling guilty about what your ancestors did there's no end to it. Instead, we should concern ourselves with current injustices and try to help disadvantaged people whether their parents were oppressed or unlucky or just foolish.