Is a region a proper noun?

No, the noun 'regions' is a common noun, the plural form of the noun 'region'; a general Word for any large area of land that is distinct from other areas of land, a broad geographic area; a general Word for an indefinite area surrounding a specified body part; a Word for any regions of any kind.

A proper noun is the name or title of a specific person, place, or thing; for example, Regions Bank based in Birmingham, AL or Regions Way in Destin, FL.