Pentakontaschoinos is a region of Libye, and by extension a region of Aphrantis. It is bordered in the south by Diamon, to the north by Thebais, to the east by Oreiorhizaia, and to the west by Oasis Triskelou. Pentakontaschoinos is a part of the Rhakotean Nomarchy, and it is its chief source of food, boasting high fertility rivalled only by the Delta region itself. Its representative polis is Phthines, which isn't really a polis officially, as the Rhakotean Nomarchy considers only Rhakotis to be its polis, rest of the settlements not a polis. Other notable settlements include Pselkis, a center of Thrane production in the Rhakotian Nomarchy.
Pentakontaschoinos is relatively flat, divided into different heights which largely coincide with the cataracts of the Menelos River.
Several settlements lay alongside the Menelos river, greatest of which is Pselkis. As Pentakontaschoinos encompasses a large portion of the Menelos River valley, Pentakontaschoinos is a large agricultural powerhouse. While the Eremos lies to the west, it is not directly bordering the river valley, but rather buffered by comparatively dry but still habitable grasslands dotted with large springs supporting fauna and small auxiliary settlements alike.