sentences:  As Hu Zongnan's force withdrew to western China, the Ma clique's force became the major nationalist force responsible for the defense of the northwestern China.Lanzhou, the largest city in northwestern China was critical to the security of the entire northwestern China and on the northwestern China joint defense conference held in Guangzhou, the nationalist defenders planned to defeat the enemy at the gate of the city of Lanzhou with the help from their comrades-in-arms from southern Shaanxi, southern Gansu and Ningxia.Defenders