In 184, concurrent with the outbreak of the Yellow Turban Rebellion in large parts of China, the Liang Province rebellion commenced. Han campaigns to retake the area remained inconclusive, and by 189 Liangzhou was a de facto independent warlord state ruled by Han Sui and Ma Teng. Warlord Cao Cao started an offensive against Liang Province in 211, winning a key victory in the Battle of Tong Pass (211), and finally conquering the entire province in 215.