Why some effects of colonization still affect society today

One of the effects of colonisation was the drawing of borders, especially in Africa, not according to the tribal divisions- see how straight the borders are there, this is actually quite unusual.
This means that while people in the same country don't always speak the same language, people in the neighbouring country might speak the language of a minirity in another country - and this minority can then be prosecuted by the majority that might feel hostile towards it.

This is just one of many examples; there are many others!