Anything but air units, that’s right.
Plus, you can send mech and tanks through to a second friendly territory.
Example:
You’re the UK and you control Alexandria and Trans-Jordan.
You invade and conquer Egypt.
If you left a mech or tank behind in Alexandria, during non-combat you can move them to Trans-Jordan. Additionally, if you had mech or tanks in Trans-Jordan that hadn’t moved, you could move them to Alexandria. You could actually do both at the same time (mech one way, tanks the other, of course. Sending the same units back and forth would have no effect).