The Regions tab shows regions you defined in your design. It also shows instances assigned to that region.
Hierarchy Window - Regions Tab
In this view, you can right-click a region and select Properties to display its properties (name, type, extents, and resource usage). You can also change a region's color in its Properties dialog box.
Additionally, from this view, you can assign an instance to a region, unassign instances from a region, and delete a region.
Note: To assign an instance to more than one region, those regions must be overlapping.