Ludwig IV of Thuringia was a German nobleman who lived during the 13th century, specifically from 1200 to 1227. He was a member of the House of Wettin and served as the Landgrave of Thuringia. His reign was marked by efforts to strengthen his territory and improve its governance. Ludwig IV is also known for his involvement in the Crusades, where he participated in military campaigns aimed at expanding Christian influence in the Holy Land. His leadership and alliances helped to solidify the power of Thuringia during a time of political fragmentation in Germany.