[26][27] Having excelled both in battle and diplomacy, Bumin declared himself Illig Khagan of the new khanate at Otukan, but died only months later.

This western branch of the Ashina clan was de facto independent while the eastern khagan was formally recognized as the senior.

The alliance with China was further reinforced in 568 through the marriage of the Turkic princess Ashina, daughter of Muqan Qaghan, with Emperor Wu of the Xianbei-led Chinese Northern Zhou dynasty.

The appearance of the Pannonian Avars in the West has been interpreted as a nomadic faction fleeing the westward expansion of the Göktürks, although the specifics are a matter of irreconcilable debate given the lack of clear sources and chronology.

[33] As for the southern borders, they were drawn south of the Amu Darya, bringing the Ashina into conflict with their former allies, the Sasanian Empire.

[36][37] The second contact occurred when Maniah, a Sogdian diplomat, convinced Istämi (also known as Silziboulos in Greek writings[38]) of the Göktürks to send an embassy directly to the Byzantine Empire's capital Constantinople, which arrived in 568 and offered silk as a gift to emperor Justin II and where they discussed an alliance.

[citation needed] Istämi's son, Tardu the leader of the western Türks, made a bid for total independence.

[27] Tardu attacked Chang'an, the Sui capital, around 600, demanding Emperor Yangdi end his interference in the civil war.

The Shibi Khan (609–619) and Illig Qaghan (620–630) attacked the Central Plain at its weakest moment during the transition between the Sui and Tang.

Shibi Khan's surprise attack against Yanmen Commandery during an imperial tour of the northern frontier almost captured Emperor Yang, but his ethnic Han wife Princess Yicheng—who had been well treated by Empress Xiao during an earlier visit—sent a warning ahead, allowing the emperor and empress time to flee to the commandery seat at present-day Daixian in Shanxi.

[49] This was besieged by the Turkic army on September 11, 615,[50][51] but Sui reinforcements and a false report from Princess Yicheng to her husband about a northern attack on the khaganate caused him to lift the siege before its completion.

On September 23, 626,[50] Illig Qaghan and his iron cavalry reached the bank of the Wei River north of Bian Bridge (in present-day Xianyang, Shaanxi).

[52] On the third day after the meeting, the khan sent 3,000 horses and 10,000 sheep to the border to be prepared as compensation for the Tang dynasty, which Emperor Taizong did not accept, believing that this was too little.

[33] Before mid-October 627, heavy snows on the Mongolian-Manchurian grassland covered the ground to a depth of several feet, preventing the nomads' livestock from grazing and causing a massive die-off among the animals.

In 627 Tung Yabghu, assisted by the Khazars and Emperor Heraclius, launched a massive invasion of Transcaucasia which culminated in the taking of Derbent and Tbilisi (see the Third Perso-Turkic War for details).

In April 630 Tung's deputy Böri Shad sent the Göktürk cavalry to invade Armenia, where his general Chorpan Tarkhan succeeded in routing a large Persian force.

[citation needed] The Western Turkic Khaganate was modernized through an administrative reform of the Ashina clan (reigned 634–639) and came to be known as the Onoq.

The era spanning from 657 to 699 in the steppes was characterized by numerous rulers – weak, divided, and engaged in constant petty wars under the Anxi Protectorate until the rise of Turgesh.

Türk remains analysed displayed on average c. 62% Ancient Northeast Asian, c. 27% Western Steppe Herders, and c. 11% BMAC-associated ancestry.

A sample belonging to the Ashina tribe, the ruling clan of the Göktürks, was found to be nearly entirely derived from Ancient Northeast Asians (96-98%) and also displayed affinity for the Slab-grave culture.