Go into the mis file, you can do this with Tribal IDE or notepad and look for the terrain datablock, it should say the terrain file. If it isn't what the map name is, odds are that its a serverside terrain file, the one you used to make the map. To make a terrain file, you have to edit the terrain itself, a good way to do this if you don't want to move it, paint it. It will act as a new terrain so when you save it, it should have saved in the base/terrains file, if you don't have that folder I suggest creating it first.
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