Post hoc, ergo propter hoc

I considered this issue on the basis of upper words.

The colored people tend to have been seen as the inferior races. And the discrimination against those people, especially against black people is deeply rooted, continuing and will be never disappeared as long as there are differences of skin colors. the custom have been inherited from generation to generation. And even now, there are many children suffering from being forced to work regardless of their wills because of the deep rooted stereotypes. So the old custom must be the cause of colored people.

The upper word is the word that means the fallacious claim, or assumption that because A occured after B, B must have been the cause of A.

There are some refferences like this, I suspect that we should believe those info because of the simple reasoning.