Who is Tiger-Fighting General Li Zhong from Water Margin and what is their importance?

It is this man whom Shi Jin and Lu Da meet at Weizhou selling medicine and putting on an arms show. He is one of Shi's old arms teachers. Du La again meets up with this man on Peach Blossom Mountain. Li had become the leader of a pack of bandits on the mountain who rule the area. The Peach Blossom Bandits eventually merge with the Liangshan Marsh bandits. At this point, Li is named a lieutenant commander in the bandit forces. He is one of the troops who assist Lu Junyi in his assault on Shezhou and Yuling Pass.