You don't want to make a map of 10k by 10k with an elevation of 2000 meters. That's the first problem. It's a common question for new developers and we have a number of responses on it on the forums, but there just aren't games, and has never been an online game with 2000 meters of vertical span. But even more so, think about what an area is. An area is a single unit of server simulation.
It's a common instinct to want to press a button and have a giant world laid out in front of you, but you don't want to do that. You have to think about gameplay spaces, where heavy and light traffic is, what a player will actually see, paths from point of interest to point of interest, etc. Until you've implemented major game systems, you don't want to implement anything more than a handful of areas, as you'll find yourself having to completely rethink how you lay our your game along the way.