Hi there! Part of your question is, essentially, ‘why didn’t I learn about this’. We’re happy to let the question stand, but there are a variety of reasons why you may find it hard to get a good answer to this question on /r/AskHistorians.

Firstly, school curricula and how they are taught vary strongly between different countries and even even different states. Additionally, how they are taught is often influenced by teachers having to compromise on how much time they can spend on any given topic. More information on your location and level of education might be helpful to answer this question.

Secondly, we have noticed that these questions are often phrased to be about people's individual experience but what they are really about is why a certain event is more prominent in popular narratives of history than others.

Instead of asking "Why haven't I learned about the Armenian Genocide", considering asking "What importance do scholars assign to this event in the context of Turkish/Armenian/World War I history?" - the latter question is often closer to what to what people actually want to know and is more likely to get a good answer from an expert.

Thank you!