River Rhanna

The River Rhanna is the huge river which meanders across the Great Plain of Tethas. It and its many tributaries drain most of eastern Orithea: The rains that fall on Urem, Thyria, Kamuria, most of the Suagir steppe, northern Istrium, and southeast Shandara all eventually find the sea by way of the River Rhanna. It empties into the Bay of XXXXXX on Urem's northeastern coast, and thus to the Scarlet Sea. 
The Rhanna has historically been the backbone of trade, commerce, and civilization throughout Urem. It provides a watery highway for goods from all over the north (Thelbir lands, Tirnavon, etc.) to be easily moved as far south and west as Cesynia (and thus on to the Sarpic Seas and Rhydain), and vice-versa. The Kirdan Empire's modern heartlands, richest provinces, and biggest cities mostly lie along the Rhanna or its major tributaries, as did the biggest pre-Kirdan Uremite kingdoms. These cities include Baribur, Kathakaion, Suradis, XXXXX, XXXXXXX, and XXXXXXX. 
Major tributaries of the Rhanna include the Vauxa, XXXXXXX, XXXX, XXXXX, and XXXXXXX rivers. 
Etymology: The River Rhanna's name is ancient, and comes from an archaic Tuvai root meaning simply "the great" or "the great one" (possibly related to the root "rhanta," which means "on high" or "the higher one," as in the Rhantaseppa). It could be interpreted to mean "the great river" or "the king of rivers," or more straightforwardly, "the biggest river."