In 683, Ashina Gudulu attacked Wei Prefecture (蔚州, roughly modern Datong, Shanxi) and killed its prefect LI Sijian (李思儉).
In Emperor Ruizong's Chuigong era (685-689), Tang Xiujing was made the deputy commandant of Anxi (安西, headquarters at Suyab (near modern Tokmok, Kyrgyzstan)).
Around 692, Tang Xiujing suggested to her that a military campaign be launched to recover four important garrisons that had been lost to Tufan -- Qiuzi, Yutian, Shule, and Suyab.
In response, Wu Zetian commissioned the general Wang Xiaojie, assisted by Ashina Zhongjie (阿史那忠節), to attack the Tufan forces of the region.
In fall 700, the Tufan general Khu Mangpoje Lhasung ("Qumangbuzhi" (麴莽布支) in Chinese) attacked Liang Prefecture and put Changsong (昌松, in modern Wuwei) under siege.
Tang Xiujing was set to engage them at Hongyuan Valley (洪源谷, also in modern Wuwei), but his subordinates were distressed by the shiny armor that the Tufan forces were displaying.
It was said at the time that Tang was familiar with border affairs, as far east as Jieshi (碣石, in modern Qinhuangdao, Hebei) to the four garrisons of Anxi, knowing about all of the geographic features and defensive frameworks.
As of 703, Tang Xiujing was serving as the minister of defense (夏官尚書, Xiaguan Shangshu) and still in titular command of the armies around Liang Prefecture, when he was given the designation Tong Fengge Luantai Sanpin (同鳳閣鸞臺三品), making him a chancellor de facto.
Later that year, when fellow chancellor Wei Anshi submitted an indictment against Wu Zetian's lovers Zhang Yizhi and Zhang Changzong, Wu Zetian had Wei and Tang investigate, but before investigations could be complete, there were reports that Khitan and Xi were set to attack the northeastern border, and she gave Tang the additional titles as the commandant of You and Ying Prefectures (headquartered in modern Beijing) and protectorate general of Andong to defend against Khitan and Xi.
Before Tang was set to depart the capital Luoyang, he secretly spoke with Li Xian, stating, "The two Zhangs depend too much on the favors of the emperor and have lost their proper places as subjects.
He soon made Tang Zuo Pushe (左僕射), one of the heads of the executive bureau of government (尚書省, Shangshu Sheng) and still chancellor with the Tong Zhongshu Menxia Sanpin.
It was said that Tang was not content in his retirement and, seeking to return to chancellor position, had his son marry the adopted daughter of one of the powerful women at Emperor Zhongzong's court, the senior lady in waiting Lady Helou, and in winter 709, he was again made chancellor with the Tong Zhongshu Menxia Sanpin designation, drawing much popular criticism, although he was also praised for using his wealth as a duke to help his clansmen and reburying deceased ones properly.
In summer 710, Emperor Zhongzong died suddenly—a death that traditional historians believed to be a poisoning by his powerful wife Empress Wei and daughter Li Guo'er the Princess Anle.