I think everyone else hit the nail on the head as far as the wealthy being educated. History as an educational subject in school is relatively modern. I’ve seen my grandparent’s history textbooks from the 30s and 40s since they kept them. They focused primarily in European and American history, but they aren’t nearly as detailed as the stuff I learned in my APUSH and AP Euro classes 10-12 years ago. Modern communication has helped piece together primary and secondary sources to tell a more complete narrative of what has happened. I have a friend with a PhD in archaeology, and she says what we know about history is constantly changing with the more we uncover. She is a mummy doctor, so you gotta believe her after all.