This can say a number of things about a society.
It can simply say that the society is made up of human beings. People seem to be naturally predisposed to form "us" and "them" groupings and to be loyal to "us" and hostile to "them." Thus, discrimination and oppression have tended to be a "normal" part of the human experience.
It can also say that the society has not cared enough to create and enforce laws against such oppression. While discrimination may be normal for human beings, many societies enact laws to prevent it. They use the laws to try to counteract the bad aspects of human nature.
Finally, it can say that the society lacks social mobility. It can say that people from the oppressed group are not allowed to assimilate into society. If they were, the dominant group would be much more likely to stop oppressing them.
The rise of Hitler in Germany is an appropriate analogy for understanding the role of oppression within a large group. Hitler was quite unremarkable as compared to the attributes of history's other leaders. What he did do was to communicate well. He used his gift as a way to highlight the condition of poverty that was experienced at the time by most Germans. Germany was quite poor and searching desperately for an answer to their economic troubles. The Jewish people had a history of being displaced from their homelands, and they were immigrants into Europe. By comparison, there were more Germans than Jewish; however, they had a culture of education and achievement. Hitler was masterful at attributing the economic pressures felt by most Germans on the fact that many of the university professorships and banking institutions were run by Jewish scholars and academics. He used a group mentality for turning the Germans against the Jewish by holding a small, unpopular group responsible for the poverty felt by the majority of Germans in their own homeland. It was an effective tactic.
Psychology research has shown it only takes 5 % of a population to cause approximately 95% of the remaining population to follow their lead! That was at the heart of the oppression of the Jews in Germany, and it is what is activated during the oppression of most. Think of the prevailing United States culture. Our leaders are quite powerful. With the 24 hour news cycle offered by CNN and Foxnews, many people watch a limited number of leaders and follow their words blindly...especially if the 5% sentiment is something that would benefit the larger group.
So this question should yield a response reflecting the importance in knowing your own believe system and resolving to act on your own beliefs and not the words of others. You can be a part of the 5% leaders that change the world or part of the 95% of followers...like sheep. Certainly oppression of a weaker group is wrong, but is it possible that a small numbers of a weak group could conceivably impact the greater population? Think about it.