The first-generation Pokémon games take place in the fictional region of Kanto.
Kanto is the setting of Pokémon Red, Green, Blue, and Yellow. Players travel through towns, routes, caves, and the Pokémon League while collecting the original 151 species and challenging eight Gym Leaders.
The name Kanto was not used in the first-generation games themselves. It was established more explicitly in the second generation, when players could return to the earlier map after completing the Johto adventure. That delayed naming is a common source of confusion.
Kanto is also the real name of a major region of Japan, including Tokyo, but the Pokémon setting is a fictionalized version rather than a literal map. Later regions, including Johto, Hoenn, and Sinnoh, introduced new landscapes, characters, and Pokémon while preserving the series’ basic adventure structure.