A notable feature of this map is the English possession of Western France, which means that it's no later than 1453, when France took Bordeaux. Since in the Diplomacy game you color only the ownership of "supply centers" (represented by circles on the map, the larger industrial/population centres) this is consistent with France owning Paris, Rouen and Dauphine and the rest of the provinces being "unimportant" - the same with Wales, as it's not a "supply center" then it cannot have an owner and it being without color does not imply Wales being independent from England.
Another feature is an unified Denmark, Sweden and Norway, which happened from 1397 as Kalmar Union.
This year is also consistent with a Castile without Aragon, possession of Kiev by Poland-Lithuania and Bulgaria owned by Ottomans.
The only liberty taken seems to be a bit overly unified Germany-Brandenburg.