Sites can be arranged geographically using regions. A region might represent a continent, country, city, campus, or other area depending on your use case. Regions can be nested recursively to construct a hierarchy. For example, you might define several country regions, and within each of those several state or city regions to which sites are assigned.
In a future Nautobot release, regions may become another Location Type, and the Region model may be collapsed into the Location model.