Regional groups are former local groups that were split up because there were too many members in them or because the distances were simply too far away.
This form of group is for members to network with each other regionally. Since each member is known through their local group, they can network and share information outside of their group. Information can thus be contributed to multiple local groups at the same time. To manage this a bit, each local group can send a moderator to the parent group so that someone there represents the group.
The purpose of this group is not to persuade members to do anything, but to open it up and connect them with others. Otherwise, it's like a local group, except with the restriction on the number of people. Regional groups can exist several times in a row, depends on how far apart they are.