It seems a bit glitchy in places, and unclear in others, but after banging at it a little more, it appears that...
There's two "gift" locos, possibly supposed to be available at level 10, but I didn't get them until level 11, when I got a repeat of the "Region unlocked" sequence. You have to click on the "containers" screen to get them, but it's not at all obvious where.
The containers don't all go to the first Region -- but it's random, so it doesn't matter where one is at the time.
As Rolf says, you can't move locos between Regions. You can use dismantling from one to help build up those in the other, however.
