1451
"No nation is older than 250"
(lemm.ee)
Transcript
A threads post saying "There has never been another nation ever that has existed much beyond 250 years. Not a single one. America's 250th year is 2025. The next 4 years are gonna be pretty interesting considering everything that's already been said." It has a reply saying "My local pub is older than your country".
There are people in the US for whom the whole world is whatever region they're currently living in. Sounds like they encountered some of those.