Johto introduced the second generation of Pokémon species.
The Johto region debuted in Pokémon Gold and Silver, released in Japan in 1999, and in Pokémon Crystal. These games added 100 new Pokémon, expanding the National Pokédex from the original 151 to 251 species.
Johto includes locations such as New Bark Town, Cherrygrove City, Goldenrod City, Ecruteak City, and the Indigo Plateau. Its Gym challenge uses eight badges, and the story introduces features including Pokémon breeding, held items, a day-and-night cycle, and Pokémon eggs.
Johto is closely connected to Kanto: after completing the main Johto adventure, players can revisit Kanto in Gold, Silver, and Crystal. That connection sometimes causes the regions to be conflated, but Johto is the region associated with Generation II’s new species. Kanto is the original Generation I region, while Sinnoh and Unova arrived in later generations.