The region in Pokémon Ruby and Sapphire is Hoenn.
Ruby and Sapphire are the third-generation main-series Pokémon games. They introduced Hoenn as a new setting, with a map inspired partly by Kyushu, Japan. The region contains coastal routes, islands, forests, deserts, volcanic areas, and the underwater routes that became a notable feature of the games.
Hoenn also introduced 135 new Pokémon, including the starter trio Treecko, Torchic, and Mudkip. The games’ central conflict involves the villainous teams Team Magma and Team Aqua, whose competing plans threaten the natural balance of land and sea.
Kanto is the setting of the first generation, Johto belongs to Gold and Silver, and Sinnoh is the region of Diamond and Pearl. Those names are sometimes confused because the games frequently revisit earlier regions and connect their stories through recurring characters and Pokémon.