Tian Kehan (Chinese: 天可汗; pinyin: Tiān Kěhán; Wade–Giles: T'ien K'ehan) also translated as Heavenly Khagan, Celestial Khagan or Tengri Khagan, was a title addressed to Emperor Taizong of Tang by various Turkic nomads. It was first mentioned in accounts on May 20, 630 and again on October 24, 646, shortly after the Eastern Turkic Khaganate and Xueyantuo were annihilated by Emperor Taizong's generals.
The title Tengri Khagan also used to refer another Turkic ruleres, both known as the Dengli Khagan(Chinese: 登里可汗or 登利可汗) or Täŋridä qaγan(Chinese: 騰里可汗)to the Chinese, during the Second Eastern Turkic Khaganate (r. 739–741) and Uyghur Khaganate (r. 759–779) periods.
It is not certain whether the title also applied to the rest of the Tang emperors, or to the empress Wu Zetian, since the term "Kaghan" only referred to male rulers and Empress Wu had started her dominion in the Chinese court after the year 665 AD until the year 705 AD, which is after the title's first use by a Chinese emperor. However, we do have two appeal letters from the Turkic hybrid rulers, Ashina Qutluγ Ton Tardu in 727, the Yabgu of Tokharistan, and Yina Tudun Qule in 741, the king of Tashkent, addressing Emperor Xuanzong of Tang Li Longji as Tian Kehan during the Umayyad expansion.
- Liu, 79
- Kenneth Scott Latourette (1964). The Chinese, their history and culture, Volumes 1-2 (4, reprint ed.). Macmillan. p. 144. Retrieved February 2012 8. "territories within his empire. He took the title "Heavenly Khan," thus designating himself as their ruler. A little later the Western Turks, although then at the height of their power, were badly defeated, and the Uighurs, a Turkish tribe, were detached from them and became sturdy supporters of the T'ang in the Gobi. The Khitan, Mongols in Eastern Mongolia and Southern Manchuria, made their submission (630). In the Tarim basin"
- Liu, 74-76
- Liu, 81-83
- Bai, 230
- Xue, 674-675
- Michael Robert Drompp (2005). Tang China and the collapse of the Uighur Empire: a documentary history. Volume 13 of Brill's Inner Asian library (illustrated ed.). BRILL. p. 126. ISBN 90-04-14129-4. Retrieved February 2012 8. "the successes of Tang Taizong and to his taking the title of "Heavenly Qaghan" at the request of "the peoples of the northwest" in 630/631. The letter goes on to describe how Taizong's envoy was sent to pacify the Kirghiz in 632/633 and how in 647/648 a Kirghiz chieftain came to the Tang court where he was granted titles, including commander-in-chief of the Kirghiz (Jian-kun). All of this implifed Kirghiz suboordination to Tang authority, at least in Chinese eyes. According to the letter, Kirghiz tribute had come to the Tang court "uninterruptedly" until the end of the Tianbao reign period (742-756) when Kirghiz contact with the Tang state was cut off by the rise of Uighur power in Mongolia."
- Bai, Shouyi et al. (2003). A History of Chinese Muslim (Vol.2). Beijing: Zhonghua Book Company. ISBN 7-101-02890-X.
- Liu, Yitang (1997). Studies of Chinese Western Regions. Taipei: Cheng Chung Book Company. ISBN 957-09-1119-0.
- Xue, Zongzheng (1992). A History of Turks. Beijing: Chinese Social Sciences Press. ISBN 7-5004-0432-8.