Hello Rebecca,
The info from Ancestry indicates that the regional origins relate to inhabitants from those areas a couple of thousand years ago.
Matches will only be from people who have also done the Ancestry DNA test and have some similarities to your DNA. If you have a reasonably researched tree on Ancestry going back at least 4-5 generations, anyone with a tree also on Ancestry with ancestors at some point identical to yours, will come up as a match to you. Your tree and theirs will be displayed side by side back to the common ancestor.
The predominant results are from people in UK, USA and Australasia, with a very small no. from Europe.
The results don't appear to be as precise as we would like since we get half our genes from each parent and then only a part of each parent's DNA makeup, so we are not identical to siblings.
Like you, we have matches that don't seem to have links that the closeness of relationship suggests. In one case we have a reasonably close match in USA, but the tree for that person has no-one even close to a match for many generations back. I wonder if something went on behind the sheltershed that no-one knows about or wants to know about?
In another instance, 2 sisters come up as different generation relations to my wife.
While the results are very interesting, there is still a fair amount of explanation needed to grasp the implications in some cases.
I also wonder if fluke combinations show up as matches when in reality they aren't genealogical matches.
Best wishes,
Garry