Which Pokémon generation introduced the Johto region?

Generation II introduced the Johto region.

Generation II began with Pokémon Gold and Silver, released in Japan in 1999 and internationally in 2000. These games expanded the original formula with 100 new Pokémon, bringing the series’ total from 151 to 251. Johto is the main setting, with locations such as New Bark Town, Violet City, Ecruteak City, and Goldenrod City.

The generation introduced several lasting mechanics, including Pokémon breeding, held items, a day-and-night cycle, Pokémon genders, and friendship-based evolution. It also connected Johto to Kanto, allowing players to revisit the region from the first-generation games after completing the main Johto storyline.

Generation II is sometimes confused with Generation I because Gold and Silver include Kanto and many original Pokémon. The distinction is chronological and structural: Kanto and the first 151 species belong to Generation I, while Johto and its additional 100 species began Generation II.