Wiki Interactive Map: Bigger than in-game map

Something weird I've just noticed: The interactive maps on a lot of the Wiki articles use a map which is actually bigger than the one in-game. It includes a huge chunk of land east of the currently exploreable area.

I can't find a way to link directly to the map, but if you go to any page with an interactive map, the Blazeridge Steppes page for example, scroll down to the map then zoom it out you'll see the area I mean. It looks like there's a lot of land east of Ascalon we've never seen or heard anything about.

Does anyone know where that map came from? It looks pretty seamless and in the same art style so I assume it's something from Anet and not a fan addition, but I don't think I've ever seen it before.

The same amount of map appears on that_shaman's Historical Guide To Tyria, so maybe it's datamined? That's just a guess though. I agree that it looks official, and it would make sense for the artists to draw a bigger map than was actually needed at release, so that it could be expanded without having to add bits on.

Its not datamined, its the actual map.But the ‘image’ that loads ingame is larger than the borders that can be scrolled past.I think its intended as a buffer on the edges in case they add a map that needs to push the boundaries