Abaoji’s western campaign: the Khitans reach the Orkhon

After the Yenisei Kyrgyz destroyed the Uyghur Khaganate in 840, they did not, in the view of the historian Michael Drompp, keep a significant presence on the Mongolian plateau, and no lasting power held it until the Khitans. Abaoji of the Yelü clan, khagan of the Khitans from 907 and emperor from 916, subdued his neighbours one by one. The Liao history records that in the sixth lunar month of 924 he summoned the empress, the heir, the commander-in-chief, the chancellors and the tribal chiefs and told them — to their alarm, for none understood him — that “three years hence, in the bingxu year, at the beginning of autumn” he would have “a place to return to”, but that two tasks remained unfinished. The same day, 22 July 924, he launched a great campaign against the Tuyuhun, the Dangxiang (Tanguts) and the Zubu, leaving his heir Bei as regent and taking with him his second son, the commander-in-chief Yaogu, the future emperor Taizong.

The army marched west for two months, making sacrifices on mountains along the way; on 29 September it camped in what the annals call “the old land of the shanyu”, the title of the ancient Xiongnu rulers. On 1 October 924 it reached “the old Uyghur city” — most probably the ruins of the Uyghur capital Ordu-Baliq (Khar Balgas) in the Orkhon valley — and Abaoji had a stone carved to record his achievements; on 5 October he worshipped the sun at a place called Dailin. Detachments raided the Zubu, and on 29 October he ordered the old stele of a khagan whom the Liao history calls Pi'e to be ground smooth and a record of achievements cut on it in Khitan, Turkic and Chinese characters. In the next month his troops crossed the “Flowing Sands”, took the town of Futu and, in the words of the annals, “seized all the tribes of the western borderlands”; late in November 924 they captured a governor of the Uyghur kingdom of Ganzhou in Gansu, and Abaoji sent envoys to its ruler, the Wumuzhu khagan.

According to a letter written two centuries later by Abaoji’s descendant Yelü Dashi and preserved in the Liao history, Abaoji offered to give the Uyghurs back their ancestral land; the khagan of Ganzhou declined, answering that his people had lived in their new home for more than ten generations and would not move again. In May 925 the Uyghur khagan sent envoys with tribute and thanks, and a Uyghur embassy at the Khitan court in these years is credited with inspiring the Khitan small script devised by Abaoji’s brother Diela. Abaoji came home on 23 September 925. On 3 January 926 he declared that of his two tasks one was done and only the hereditary enemy, Balhae, remained, and marched east; he destroyed Balhae that year and died at Fuyu on 6 September 926 — in the bingxu year, at the beginning of autumn.