Tardu

Tardu or Tardush Yabghu was the second yabgu of Western Half of Turkic Khaganate (c. 575–603), and Ninth Khagan of the First Turkic Khaganate (599–603). He was the son of Istämi.
Names.
The regnal name in Turkic was Tarduš (), Medieval Greek: Ταρδου, 達頭可汗/达头可汗, Pinyin: dátóu kěhàn, Wade-Giles: ta-t'ou k'o-han, personal name: 阿史那玷厥, āshǐnà diànjué, a-shih-na tien-chüeh). According to Lev Gumilev his personal name was Kara-Churin-Turk (Кара Чурин Тюрк). However, when he subjugated Eastern half after death of Tulan Qaghan, he assumed regnal name Bilge (Wise) Khagan.
Background.
Turkic Khaganate was a vast khaganate (empire); from Manchuria and Chinese wall to Black sea. It was impossible to govern the whole khaganate from a certain capital. So while the eastern part was directly ruled by the khagan (emperor), the western part was governed by yabgu (vassal) in behalf of the khagan. The capital of the west was Ordukent (Suyab) (present day Kyrgyzstan). Istemi who was the khagan's brother was the first and Tardu (İstemi's son) was the second yabgu.
Years of civil war.
Tardu became the yabgu in c. 575. In that year he met the Byzantine ambassador Valentinius. Being a very ambitious yabgu he was planning to seize power in whole khaganate. He saw his chance in 581 when khagan Taspar died. Taspar had announced his preference for Talopien (son of Mukan Khagan) instead of his son Anluo. But Göktürk kurultay (council of tribal leaders) which was authorized to appoint the new khagan refused the former kagan's will and appointed the former khagan's son who in turn acknowledged Ishbara Qaghan as the new khagan. This gave Tardu the necessary cause to interfere. He sent an army to back Talopien. Ishbara applied Sui China for protection and both contestants were played off against each other by China.
Later years.
While the east part of the khaganate suffered from civil war, Tardu was waiting for a suitable moment to realize his plans. After the Battle of Blarathon in 591 in Sassanid Persia, Bahram Chobin who was a short term Sasanid empreror, sought asylum in Western Turks.
In 599 Tardu declared himself to be khagan of the united khaganate (east and west) But his new status was not recognised widely. Probably to persuade the kurultay, he began a campaign against China. But unlike Turks of eastern part his target of campaign was too far away and his army suffered intensely from the poisoned waterwells during the long expedition through the steppe. Finally, he had to retreat without serious combats. But this defeat was disastrous for him. After a rebellion of his subjects, he disappeared from the scene (probably was killed) in 603 or 604.
He was succeeded in west by Niri Qaghan, a son of Talopien.
Family.
He was father to Tulu (都六) and Külüg Sibir. Sheguy and Tong Yabghu were his grandsons through Tulu.