In the 14th year of Tianqi era of Tang, after wandering in the extreme coldness for thousands of years, the Desolate Tribe finally returned south to conquer the large piece of grassland from the hands of Left-Tent palace. This directly caused the palace cavalry to harass and attack the southern part of Central Plains. In order to manage the unprecedented crisis, the West-Hill Divine Palace announced an edict to gather all believers of Haotian Taoism and allies to assist Yan Kingdom in fighting against the barbarians.
At the same time, Tang Empire would send an army from the West Road to fight along with Yan Kingdom and assist Yan soldiers in all ways.