You really want to get into this?The largest? That's a dubious claim, and the goalposts move considerably depending on what period of history we are discussing.
In Europe it is.. Find a other landmass at the same size in Europe which haven't been returned after it were conquered by one nation from another..
Only a swede would call it dubious claim for a non aparent reason.![]()
Scania = 10,939 km² according to Wiki. Let's see:
Northern Ireland/Ulster? Wiki says 13,843 km2. Never reunified with Ireland 'til today.
Elsass-Lothringen? 8,280 km² + 23,547 km2, let's say 30000 km2. Never returned to Germany (HRE) after France conquered it... last lost in 1945.
Artois/South Flanders? 4000 km² + ~5000km², let's say 9000km² Never finally returned to Flanders/the Low countries after France conquered it...
Anatolian parts of Greece (as successor state to Byzantium)? Even if limited just to areas which were Greek up to the genocides of the Young Turks, this is a HUGE area.
But if your point was, Skåne is the only area which was actually sold by its former owner at one point, then I concede.