It could be the Pelagian Empire, Ozia, or possibly Eluvatar.
Ozia doesn't really take over things until the 1000s, but they do have a strong commercial presence in the area and an early mathematics/philosophy tradition. Likewise the same with Eluvatar I think? The Pelagian empire stretched pretty far in the 0s time, again I think?
Need to consult Myroria/Eluvatar
The standardized calendar doesn't necessarily need to have been imposed on everyone until the 1000s.
