Christ anon, are you new?
Gen 2 was intended to be an escalation of gen 1. Instead of traveling around a region of Japan, you'd traverse the entire country. Instead of just challenging gyms in each town, you'd be challenging gyms that represented entire regions - Kanto's gym was roughly where the Indigo Plateau is and had Red as its leader.
Evidently, after traveling as far west as Kyushu (the island that became Hoenn) and as far north as Hokkaido (the island that became Sinnoh), you'd loop back around, pass through Kanto, return to your hometown, and then scale Mt. Fuji.