A legitimate prince, a band of strong and well-equipped men, and a perfectly valid reason: what could happen in the Central Plains? So hard to guess!!!
“Khagan, the Prince Consort says he misses home.”
“Khagan, why do we all do whatever the Prince Consort says?”
Dear son-in-law, the grasslands are colder than the Central Plains. Put on another layer.
“Khagan, how did we become the legitimate rulers?”
“Huh? Khagan, when did you get Han Chinese ancestry?”
“Khagan, how did the Prince Consort become emperor?”
“Khagan, how did we get titles as marquises and ministers?”
“Mind your words.”
“Khagan...”
“...”
“Long live the Emperor! Long live the Emperor! Long live the Emperor!”
The Turks change their name to [Great Tang].
The Khitans have joined the Great Tang faction. The Uyghurs have joined the Great Tang faction. Tibet has joined the Great Tang faction. The Shuofang faction has joined the Great Tang faction. The Longyou faction has joined the Great Tang faction. The Guanzhong faction has joined the Great Tang faction. The Yanzhao faction has joined the Great Tang faction. The Jurchens have joined the Great Tang faction. Great Tang declares war on Zhou Wu.
The Turkic Khagan and the prince sent as a marriage alliance receive the hidden quest “The Glory of the Heavenly Khagan.” Accepting it grants the skill, use of the Qin King's Battle Formation Music. While in use, army morale increases by 200%, combat power increases by 200%, and enemy generals' inclination to surrender increases by 1000%. [Turks] have gained: strong claims over the Central Plains, legitimate casus belli, and +50% stability in occupied regions.
[Turks] officially change their country's name to [Great Tang].
[Great Tang] has declared war on [Wu Zhou].
[Wu Zhou] civil officials' loyalty: -80%; military officials' loyalty: -90%; commoners' loyalty: -99%.