Write what you know.
Not all writing instructors agree with that. Some even say it can be better to write what you don’t know. “Write what fascinates you,” they say.
Nevertheless, many authors do write what they know. It’s easier to describe places you’ve been to. It’s easier to get inside the head of a character who’s been through experiences that are similar to yours.
History, by its very nature, is unknown. You can’t rely on your experiences or on knowing a place, because they were different then.