its actually a real rabit hole to see which cultures use however many days to refer into the future and past. Since the use of unified calenders its been declining. few centuries ago it wasnt unusual to have words for like “five days ago”. and some languages actually perserved that!
Dont ask me for specifics tho. its been many moons since i did that deep dive ^^
there are offices that offer these services offline. if you wanna do it on your own youll need to request a lot of acces to city archives. At least in some countrys, citys keep many infos. including if someone moves there ect.
So if you know where your grandparents used to be born, go there, and maybe you find infos about your grand grandparents. and then its just a game to hunt for infos. See if you can find your anchestors names in unis, or companys or something.
I heard its quite tedious and takes years