he was persuaded by his old time friends to switch to Li Shimin’s troop to fight for Li Yuan's Tang Dynasty. He defeated the ally of five warlords (Wang Shichong 王世充, Meng Haigong 孟海公, Gao Tansheng 高檀晟, Zhu Can 朱灿 and Dou Jiande 窦建德) within one day. Two years later, another ally led by Liu Heita (刘黑闼), Xu Yuanlang (徐圆朗), Shen Faxing (沈法兴), Gao Kaidao(高开道) and Tang Bi (唐壁) invaded Tang Dynasty. Luo Cheng took part in this war and he was killed by a general in Liu Heita's troop, Su Dingfang (苏定方), with arrows. However, the story behind that was the envy of Li Jiancheng and Li Yuanji towards Li Shimin. Luo Cheng was actually a victim of political conflicts among Li Yuan's sons. There are much more folk stories about Luo Cheng outside of Shuo Tang, including his romantic love with Dou Jiande’s daughter Xianniang (窦线娘), and even with Hua Mulan (花木兰). His son Luo Tong (罗通) became a leading role in the sequel of Shuo Tang. The folk legends also believe that his descendant Luo Yanqing (罗延庆) was a general in Yue Fei’s troop in Song Dynasty. Another interesting fact about Luo Cheng and his cousin Qin Shubao: As mentioned before, Luo's family had special skills and tactics in using spear; similarly, Qin's family has special skills in using Jian (锏, a type of prism-shaped weapon, generally a combination of sword and short stick). One day, they decided to teach each other their special skills in private. Luo said that he would teach all he knew to Qin; otherwise he would die under arrows. Qin told Luo that he would also teach all he knew, or he would be killed by a heavy object. Ironally, Luo Cheng kept his last and the best spear tactic, the Huimaqiang (回马枪: Make a fake retreat, and then suddenly stab back to the enemy when he or she is approaching from behind). At the same time, Qin Shubao also kept his last and the best Jian tactic, the Shashoujian (杀手锏: Also make a fake retreat. When the enemy attacks from the back, Qin would reach out the Jian on his right hand backwards to ward off the enemy's weapon, and then suddenly turn around and beat the enemy with another Jian on his left hand). They thought no one knew. However, as already mentioned, Luo Cheng was finally killed by arrows