From: Eagle River, Alaska
The type terrain should not be determined by elevation alone, but by the actual change in elevation of terrain within the hex. Far too many map makers assume that high elevation means rough or mountainous terrain. Not true at all. Some of these have become engrained in wargames, like the "mountains" in Cyrenaica, Libya. There are no mountains in Libya, rather it is a high elevation plateau with an eroded escarpment facing the coastline. The area shown as mountains on all wargame maps are small hills with elevation changes of less than 100 meters. I live in Alaska and the Chugach mountains in my backyard are not particularly high in elevation (front range around 3-4000 feet summits) because they are close to the Pacific Ocean, but they are impassible mountains nonetheless. Furthermore, because of the latitude the actual alpine terrain starts around 3000' whereas in the Rockies or Alps, the treeline is around 10,000 feet. Much of western China is above 15,000 feet in elevation, but is desert, not alpine or tundra.
Bottom line is you have to use multiple sources to determine the terrain to put on a map - and don't use someone else's map as a guideline. Use Google Maps with the "terrain" function on to determine how "rough" an area is to determine whether hills, mountains, or whatever.