The French terminations -ois / ais serve as both the singular and plural masculine; adding 'e' (-oise / aise) makes them singular feminine; 'es' (-oises / aises) makes them plural feminine.
The Spanish termination "-o" usually denotes the masculine and is normally changed to feminine by replacing the "-o" with "-a".
So can those ending in -ch / -tch (e.g. the French, the Dutch) provided they are pronounced with a 'ch' sound (e.g., the adjective Czech does not qualify).
Entries in italics are continental regions (taking as reference the 7 continents model).
(References: Herodotus' "Histories"; Thucydides' "Peloponnesian War"; Pausanias' "Description of Greece"; Lemprière's Bibliotheca Classica; Leverett's 1838 edition of the "Lexicon of the Latin Language"; Freeman's "The History of Sicily..."; et al.) Ancient civilizations, former colonies, renamed countries and regions, annexations, secessions, etc.