Great Plains is the easternmost territory in the original game, bordered on the west by Tall Trees. The northern, southern, and eastern borders of the region consist of the shoreline of Flat Iron Lake. The Upper Montana River forms the northern border of the territory, with Big Valley on the other side.
The landscape of Great Plains consists primarily of rolling hills with low-lying vegetation and few trees. As such, Great Plains has the largest population of plants in one area, in all of the original game. Due to the landscape and the visual distinctiveness of the plants, they are also among the easiest to find.
This region is named and modeled after the Great Plains area of the United States, or more specifically, the Great Plains region in Northwestern Texas.