The Dark Valley
Dark Valley was part of the Onii King's territory. Once King Corobo created Farmland, he has to go through Dark Valley to fight the Onii King. The valley has various pots containing arrows and Oniis throwing pots at Corobo.
Once Corobo defeats the Onii King, Dark Valley gets renamed as "Dark Valley Nature Reserve" and is inhabited by Rodeo Cows in the valley and Black Sheepon the cliffs. Initially, this area was very dark, but becomes sunny when Corobo claims the area.