Mount Song
Hulao Pass () is a choke point northwest of Xingyang, Henan province, China in the foothills of Mount Song. It is the site of many historical battles, being the eastern guard for the capital Luoyang for several dynasties. With Mount Song to the south, the Yellow River to the north, the pass holds up a formidable defense. Many defensive structures have been set up here throughout history, dating from the Warring States period when a checkpoint is set up here. The pass became fortified in the Tang Dynasty.