Which Pokémon game series first introduced the Kanto region and its original 151-species Pokédex?

Pokémon Red and Green first introduced the Kanto region and the original 151-species Pokédex. Game Freak created the paired Game Boy role-playing games, which launched in Japan in 1996.

Kanto contains familiar locations such as Pallet Town, Viridian City, the Safari Zone and the Pokémon League. Players travel through eight Gyms while building a team from the first generation's species. Trading between versions is required to obtain every version-exclusive Pokémon.

International releases are a frequent source of confusion. Japan's original pair was Red and Green; the revised Japanese Blue became the technical basis for the overseas Red and Blue versions. Thus, “Red and Blue” is correct for many international discussions, but not for the original Japanese debut.

The Kanto setting and 151-species roster established conventions that later regions expanded with new maps, rivals, villainous teams, Gyms and Pokédex entries.