Why are most ghost dressed like they are from the 1800's?

I watch a lot of ghost things on netflix, like ghost hunters, why don't we see cavemen ghost? And could "demons" possibly be human ghost from indiginous pre historic humans who don't understand modern humanity so they just terrorise others? It just bothers me how ghost stories are all about people in the 1700-1800's ? I'd at least like to hear about ghost at aushwitz or ghost from the dead gladiators or Rome at the coliseum. Considering how many humans have lived on earth, and how many have died on the ground we walk on how come 1700-1800 ghost get the spot light???