sentences:  After a series of battles, the communists succeeded in taking nationalist strongholds including Daning (大宁), Forever Peace (Yonghe, 永 和), Pu (蒲) County, Stone Building (Shi Lou, 石楼), and heavily fortified towns Xi (隰) County and Middle Sun (Zhong Yang, 中阳).Majority of the local nationalist garrison totaling more than five thousand were captured alive by the enemy, including the nationalist commander-in-chief of the western Shanxi region of the 2nd War Zone, Yang Dengyuan (杨澄源), while the rest were killed.The rapid success of communist meant that a vast region bordered by the Yellow River in the west, the Datong – Pukou Railway in the east, Middle Sun (Zhong Yang, 中阳) in the north and the Ji (吉) County in the south had fallen into the enemy hands by December 12, 1946, and the rear of the nationalist units planned to attack Yan'an was gravely exposed, and thus seriously threatened by the enemy.