During the Tang Dynasty, Tubo, an ethnic minority state that occupied the Qinghai-Tibet Plateau for a generation, was a major problem for the Tang Dynasty, and conflicts often broke out between the two countries. After Emperor Gaozong of Tang ascended the throne, the Tang Dynasty army destroyed the Western Turk Han State, so that the Western Regions were back in the hands of the Tang Dynasty, in order to maintain the stability of the Western Regions, the Tang Dynasty set up the Anxi Capital Protectorate in the local area, and stationed tens of thousands of Tang Dynasty troops all year round, it is reasonable to say that after the Western Regions were strictly protected by the Tang Dynasty troops, the Western Regions should be at ease, but soon the Tang Dynasty army found that they underestimated the strength of foreign invaders.
During the Tianbao period, the Tubo army invaded the Western Regions for three consecutive times, and the twenty countries in the Western Regions all severed their relations with the Tang Dynasty, and Tang Xuanzong was furious, so he sent the famous general Gao Xianzhi to the Western Regions to clean up the mess. Previously, several envoys of the Tang Dynasty led their armies to prepare to subdue the western regions, but because Tubo sent troops to assist them in vain, Gao Xianzhi immediately convened a meeting after his arrival, and after several investigations, Gao Xianzhi found that the reason why the western regions fell so quickly was because a small country on the Onion Ridge took the lead in defecting, and the name of the country was called Xiao Bolu.
Originally, Xiao Bolu was an important area to guard the western region, it was the main traffic route to the four towns of Anxi, since Tubo married the princess to the king of Xiao Bolu, the country has followed Tubo and become an important stronghold for Tubo to invade the western region, so Gao Xianzhi decided to lead the army to destroy this small country first. But an important problem was in front of Gao Xianzhi, that is, in order to conquer the capital of Xiao Bolu, it was necessary to cross the towering mountains at an altitude of up to 5 kilometers and cross the Pamir Plateau, which was an out-and-out problem in ancient China.
Therefore, after sufficient preparations, Gao Xianzhi led 10,000 Tang troops to wade through the mountains and rivers, and after more than 100 days of rapid marching, finally successfully reached Bomishui, where Gao Xianzhi sent troops to quickly conquer Lianyun Fort, a major military town between Tubo and Xiao Bolu, and then crossed the Tanjuling Pass and approached xiao Bolu's capital, Ah Yue Cheng. Seeing that the divine soldiers were descending from heaven, Xiao Bolu's army surrendered to the Tang army with almost no resistance.
In order to prevent the Return of the Tubo army, Gao Xianzhi ordered the cutting off of Xiao Bolu's Vine Bridge leading to Tubo, and sent three thousand Tang troops to garrison the area. After the pacification of the Xiao bolu state, the reputation of the Tang army increased rapidly, and dozens of countries in the western region were overwhelmed, and all surrendered to the Tang Dynasty.