Little is known about Helian Duo's background, including his birth year, other than that, as of the time of Emperor Yizong, he was then a Tuyuhun chief and carried the Tang-bestowed title of commandant of Yin Mountains.
Later, when Tang imperial forces had to battle a rebellion led by Pang Xun at Xu Prefecture (徐州, in modern Xuzhou, Jiangsu), Helian participated in the campaign.
[1][2] In 878, the Shatuo chieftain Li Guochang and his son Li Keyong rose against the rule of Emperor Yizong's son and successor Emperor Xizong at Zhenwu (振武, headquartered in modern Hohhot, Inner Mongolia) and Datong (大同, headquartered in modern Datong, Shanxi) Circuits, respectively.
Helian persuaded Gao to submit to the new Tang-commissioned military governor of Datong, Li Zhuo (李琢), and Gao surrendered with the Shatuo chieftain Li Youjin (李友金), Mi, and Shi Jingcun, after arresting fellow officer Fu Wenda (傅文達).
[4] In 885, by which time Li Keyong, due to his great accomplishments in defeating the major agrarian rebel Huang Chao for the Tang imperial government, had been given the military governorship of Hedong Circuit (河東, headquartered in Taiyuan, Shanxi), both Li Keju and Wang Rong the military governor of Chengde Circuit (成德, headquartered in modern Shijiazhuang, Hebei) feared the strength that Li Keyong showed and his alliance with their neighbor Wang Chucun the military governor of Yiwu Circuit (義武, headquartered in modern Baoding, Hebei).
Li Keyong's officer An Jinjun (安金俊) was killed by an arrow, and Shen Xin (申信) surrendered to Helian.
They were concurred in by Li Keyong's rival Zhu Quanzhong the military governor of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan), as well as the chancellors Zhang Jun and Kong Wei.
They had initial successes, as Li Kuangwei captured Wei Prefecture, and Helian, along with Tufan and Xiajiasi tribesmen, attacked Zhelu Base (遮虜軍, in modern Xinzhou, Shanxi), killing its defender Liu Huzi (劉胡子).