Kanto

From Bulbapedia.

The Kanto region (Japanese: カントー地方 Kantō-chihō) is a region of the Pokémon world. It is located east of Johto, and as revealed by the radio show Sinnoh Sound, is located south of Sinnoh. It was the first region to be introduced. It is setting of the Generation I games and FireRed and LeafGreen; it is also accessible in Pokémon Gold, Silver, Crystal, HeartGold, and SoulSilver after the quest in Johto is completed.

All cities in Kanto are named after colors (Viridian City, Lavender Town, Indigo Plateau, etc.), with the exception of Pallet Town, which is also a reference to color. Professor Oak is the resident Pokémon Professor and gives Pokémon Trainers a choice between Bulbasaur, Charmander, or Squirtle as their starter Pokémon, though in Yellow the only choice is a Pikachu that he recently caught, although he did have an Eevee. In the games, the player begins his or her journey in Pallet Town and ends it at Indigo Plateau.

It is based on and named after the real Kantō region (関東, meaning "east of the barrier") in Japan. Unlike almost every other region, which are specific to their own generations, Kanto has been explorable in the first four generations of Pokémon games. However, it is not the primary region in the Generation II and IV games it appears in, in which players explore the neighboring Johto region before exploring Kanto.

The artwork of Kanto in Generation I and Generation II depict Kanto as grassland, with very few trees. In Generation III and Generation IV, Kanto is seen with more trees, making it less like grassland.