Writing advice often includes this one:
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.
Miriam Drori, Author 
3 replies on “2015 A to Z Challenge: U is for UNKNOWN”
I think writing what you know isn’t always a rule to follow. But it does tell you that research is important!
I didn’t know that. I know the British coast changes a lot, but I assumed it was washing towns away, not moving away from them!
Annalisa, writing A-Z vignettes, at Wake Up, Eat, Write, Sleep
(That comment should have been under V.) I haven’t explored the reason for that, but no doubt there is an explanation somewhere.