YSK high school history classes are only ever meant to serve as a basic introduction to your nation's history and you should not be so shocked when you learn later that it left a lot of stuff out
from /r/YouShouldKnow
YSK的高中历史课只是作为对你的国家历史的基本介绍，当你后来知道它遗漏了很多东西时，你不应该如此震惊