An alternate depiction of the Johto regionAnother alternate depiction of the Johto regionAnime-based map of the Johto region
The Johto region (Japanese: ジョウト地方Jōto-chihō) is a large area located west of Kanto. Johto and Kanto are part of a large landmass, with everything west of Indigo Plateau falling in the Johto region.
Johto's routes are numbered 29-46, starting at the route number that Kanto (in Generation II) left off from, 28. Route 28 itself actually partially stretches into Johto, though is known as Silver Cave when in Johto.
The Johto League is the regional Pokémon League of the Johto region. Johto and Kanto share a single Elite Four, located at the Indigo Plateau. Eight Johto League Badges are required to participate in League competitions.
Regardless of their proximity, the people of Johto and those of Kanto are set apart by many cultural differences. Johto is based on the real Kansai region in Japan. This trait is most noticeable in its geography; however, the Kansai influence also defines the culture in Johto. Kansai residents are known for their attitudes against typical Japanese standards, mostly due to the historical rivalry between the region, once the major seat of political power, and the real Kantō region where Tokyo, the current capital, is located. The soil of the Kansai region is rich, unlike the volcanic Kantō region, and this is perhaps referenced by the in-game Kanto region's inability to maintain a berry crop in Generation II and Generation III. People from Kansai are considered to be more relaxed. Kansai and Kantō, however different, are the two most important areas of Honshū, the largest island in Japan, and, much like Johto and Kanto, represent a harmony of contrasting cultures living together. The cultural divide is most noticeable in the games, as the player talks to and learns about the denizens of both regions.
Certain cultural aspects of the Johto region are deep-seated in Japanese history, as well. Kyoto, which is probably the basis for Ecruteak City, is considered the cultural center of Japan. Kyoto and its many historical temples, shrines, palaces, gardens and architecture have been preserved. This connection to history is reflected in many areas of Johto. However, Goldenrod City (like Osaka) is typically modern.
In the Generation IV games released so far, location pointer data (for a captured Pokémon's status screen) includes a reference to Johto, much like it does for Kanto and Hoenn when a Pokémon is transferred forward from Generation III. This may mean that Johto will make an appearance in future games compatible with Diamond, Pearl, and Platinum.
Trivia
Johto is the only main region in which Pikachu is not found in the wild, though Pikachu are available in Generation II when the player travels to Kanto later in the game.
a Gym Leader specializing in Rock-type Pokémon (however, Jasmine was originally a Rock-type trainer before Steel-types were discovered)
a Regional Pokédex (because Johto Dex from Generation II included all the Pokémon known at the time and thus isn't considered properly a Regional Dex)
an own Storage System Developer (even if Bill's hometown is Goldenrod City, he first debuted during the Kanto-based Generation I and was firstly considered as Kanto's Storage System Developer)
an own Villainous Team, because Team Rocket originally debuted debuted during the Kanto-based Generation I and was firstly considered as Kanto's Villainous Team)