Sounds like you need a userlist for each region with a filter for that region applied to the list. You'd then need to custom develop a module to display as you've provided the example with their links pointing to the userlists. You could use just plain HTML in a custom HTML module making things significantly easier however if you're willing to forfeit the count next to each region.

Groups, what do you mean specifically by this? Usergroups or groups as in GroupJive? We do not take on contract development tasks, please check sites like joomlancers and other contract developer sites. My above reply shows 2 ways to accomplish what you're wanting, 1 requiring absolutely no programming knowledge and just basic HTML in addition to understanding of userlist usage.