The northernmost portion of the state extended onto the Bundelkhand upland, whose northward-flowing rivers are tributaries of the Yamuna and Ganges. The Vindhya Range runs east and west, forming the watershed between the Ganges-Yamuna basin and the Narmada River basin, which occupies the center and west of the province, and flows westward to empty into the Arabian Sea. The upper Narmada valley forms the center of the Mahakoshal region. Jabalpur (formerly Jubbulpore) lay on the upper Narmada, and was an important railway junction.