pixel_player797907736 As you found out everything you win (events) or purchase (keys, gems, cash) go into your current (highest) region.
There is one opportunity to get ships from your previous regions but it can be iffy and expensive. Check the "Daily Offers" in the shop. In there you will find a Region Container you can buy for Gems. The Region changes each day and cycles through all your previous regions. There are two downsides to buy ships this way.
1) The cost is Gems, so if you are in region 3 then the region 2 container costs 50 gems, The region 1 container (when available) costs 40 gems. The cost goes down as you move forward through the regions. Eventually the "oldest" regions will cost 20 gems.
2) The contents, that is, the ship you get, is random based on what ships are available in the region and in no way does it guarantee you'll get something you're missing. Plus the type of ship is controlled by a random number generator so there's only 5% chance of getting a Legendary, a 15% chance of a Epic, and equal 40% chance of getting a Rare or a Common. In my experience the majority of the time I get Commons and they are duplicates of what I already have (I'm trying to get another legendary in San Francisco without much luck).
That's the only way to get ships from previous regions at the moment. It's up to you to decide if this is a good deal for you.
