The Urals and other obstacles.

http://www.axisandallies.org/forums/index.php?topic=39704.msg1651592#msg1651592

There is many posts about wastelands and mountain ranges on Asian map  discussed in this thread.

I personally like the fact that Japs have an opportunity to break through china and hurt the soviet income. gives another strategy available to them apart from calcutta crush or soviet far east breakout. Not very realistic but in terms of gameplay it’s a nice option. Plus russia can send mechs and tanks to help china, gives another option available to players. Maybe disallow moving two spaces at a time in certain territories to represent the mountains but without blocking it off completely?

I think most of the time even the Global '40 map is too zoomed out to gain much from depicting rough terrain. Any given territory is likely to contain some open fields, some hills, some forest, a small river or two, etc. I think terrain is more useful on an operational-sized map like D-Day or Guadalcanal than on a grand strategy map like the mainline Axis and Allies games.

That said, here is as far as I’ve gotten with ideas for rough terrain.

1. There is only one type of rough terrain – all swamps, mountains, forests, etc. are abstracted as “rough”. About 20% of the map should be rough terrain. This should include some but not all of Siberia and western China. For example, the Urals and Szechuan are rough terrain. Buryatia and Chinghai are not rough terrain.
2. In rough terrain, defending infantry get one free round of dice rolls before anything else is resolved. This represents the ability of infantry to ‘dig in’ and lay ambushes in caves, thickets, etc., as well as the reduced functionality of tanks and planes in rough terrain.
3. All ground units must halt after entering rough terrain. You cannot move a ground unit into a rough territory and then move it out of that territory on the same turn, except by retreating.

I believe though that aircraft should have the ability to fly over these zones.