The Sulm is a river of 83 km length in Southern Styria (Austria) which originates at the eastern slopes of the Koralpe (a north-south running mountain range in the Southeastern Alps which separates Styria from Carinthia), and flows eastwards towards the Mur through the districts of Deutschlandsberg and Leibnitz. The Sulm valley runs from the Western Styrian hill ranges to the Eastern Styrian hills and lowlands.