I saw this posted under the Season 4 changes: https://www.ageofempires.com/news/ageiv_seasonfour_update_60878/
Map Changes
General
- We’re changing the name of the Mediterranean map to Baltic.
The Baltics include Lithuania, Latvia and Estonia while the Balkans include Croatia, B&H, Montenegro, Albania (or the Eastern Mediterranean, as in the map description).
It’s a common mistake, but I think the devs meant to rename the map to Balkans.