The first-generation Pokémon games take place in the Kanto region.
Kanto is the setting of Pokémon Red, Green, Blue, and Yellow. Players travel through towns, routes, caves, forests, and seas while collecting badges and working toward the Pokémon League.
The region’s name was not used in the original Japanese games themselves. It became established in later games and related media, which can make the historical naming easy to overlook. Kanto is also the real-world name of a region of Japan, though the Pokémon setting is fictionalized.
Kanto returned in several later games, including the second-generation titles after players completed their journey through Johto. That design made it the first Pokémon region to be revisited directly in a main-series adventure.