according to the google
1. an area, especially part of a country
or the world having definable characteristics but not always fixed boundaries.
"the equatorial regions"
- an administrative district of a city or country.
synonyms: district, province, territory, division, area, section, sector, zone, belt, tract, stretch, expanse, terrain, part, quarter, locality, locale; informal parts; informal patch
"the western region of the country"
So, I though
the *province* might be an option, but it is not .