Demchugdongrub was a
Chahar born into the
Plain White Banner of the
Eight Banners in
Chahar Province during the
Qing dynasty. He was the sole son of Namjil Wangchuk, the Duoluo Duling Junwang (
Duōluō Dùléng Jùnwáng) of the
Sönid Right Banner and Chief of the
Xilingol League. His name consists of the Tibetan words "
Chakrasamvara" () and "
Siddhartha" () respectively. After Namjil Wangchuk died in 1908, the six-year-old Demchugdongrub, with the approval of the Qing, inherited one of his father's titles – the Duoluo Duling Junwang. In his youth Demchugdongrub studied the
Mongolian, Chinese, and
Manchu languages. After the fall of the Qing,
Yuan Shikai promoted Demchugdongrub to the title of
Jasagh Heshuo Duling
Jinong (
Zhāsàkè Héshuò Dùléng Qīnwáng) in 1912. Demchugdongrub married a daughter of a Taiji (Qing aristocratic title) nobleman from his own Sönid Right Banner, and the next year had their first child, Dolgorsuren ( ''Dōugǔ'ěrsūlóng
). Several years later, Demchugdongrub had four more sons and one daughter with his second wife, Fujin ( Fújìn''), a daughter of another Taiji nobleman from the
Abaga Banner.
Early political activities Demchugdongrub was appointed as a member of the Chahar Provincial Committee in 1929. In 1931, he succeeded to the post of the Chief of the Xilingol League after Yang Cang (
Yáng Sāng) and Sodnom Rabdan (
Suǒtènàmù Lābùtǎn). During September 1933, the Mongolian princes of Chahar Province and
Suiyuan traveled to the temple at
Bailingmiao north of
Guihua and gathered in a council chamber with Demchugdongrub, who for months had been trying to found a pan-Mongolian self-rule movement. In mid-October, despite their traditional suspicions of one another, they and Demchugdongrub agreed to draw up confederation documents for the Inner Mongolian banners. They sent word to
Nanjing that they intended to rule Inner Mongolia themselves. They indicated that if they were obstructed by the Chinese government, then they would not hesitate to seek assistance from Japan. In response, Nanjing sent
Huang Shaohong as an envoy, who in the end authorized the creation of the
Mongol Local Autonomy Political Affairs Committee. ==Collaboration with the Japanese==