1,3k years ago is such a weird way to write it. Makes sense if we are talking millions of years, but why not write "in 700" or just "1300 years ago"
So you can write it down to tech brainrot.
https://en.wikipedia.org/wiki/Decimal_separator#Conventions_...
Edit: "The newly-discovered manuscript in the National Central Library of Rome of Caedmon’s Hymn dates from between the years 800 and 830, making it the third oldest surviving text of the poem." So... 1.2k then?