> “On record” usually means since we started recording history , at least 5k years ago.

I'm a journalist who has published "highest/lowest on record" statistics tens, if not hundreds of times, and I've never heard of anyone thinking it means "since Herodotus" or anything like that.

How would readers know the reference point unless you inform them. Of course they will defer to colloquialisms . In some cases 5000 years , some 1000 years . With something as broad and impactful as this, they certainly assume more than 150 years .