 It has 50 tributaries, the largest being the Lichte, the Sorbitz, the Werre and the Rinne.Its name, meaning "black river", comes from its dark colour in its upper course and the thick forest which originally overshadowed the narrow valley.The Schwarza valley () parallels the axis of the Schwarzburg anticline ("Schwarzburger Sattel"), a structure that divides the Thuringian forest to the northwest from the Thuringian Highland to the southeast.