A professor of mine explained it aptly some years back, “The past is what happened, history is how we interpret it.” This was not mind-blowing but it did change my perception as a writer and a student of political science. In history, primary sources (direct sources of information like treatises, Pompei graffiti, the Cyrus Cylinder) are the best way to explain/study the past. They reflect the attitudes of the times, reveal insight into world history, and give context to events within that time period. History is often a conversation between historians, and that conversation changes with the times, prevailing criticism, and counter arguments within the study.
When it comes to writing, this is vital. Especially when you’re creating a secondary world, having an element of uncertainty works wonders both in universe and out of universe. It’s why Game of Thrones’ Maesters debate fiercely about the nature of the world, magic, and the coming changes. This is an excellent example of bringing that mentality/perspective to the world itself.