Founded by the Ashina clan of the Gokturks (or "Celestial Turks") the Second Turkic Khaghanate was a central (east) asian empire which coexisted with Tang Dynasty China.
From what we know, the Gokturks of this period had a hum.... complicated relationship with the Tang, as they were adamant about keeping their independence from them but at the same time seemed willing to coexist through diplomacy and even admired the Tang in certain aspects.
Reportedly, according to Chinese sources, the fourth Khagan, Bilga wanted to convert to Buddhism and start permanent settlements, but was eventualy persuaded not to do any of these things for fear of the loss of Turkic mobility. It's not hard to see the logic in that decision.
However, I wonder if it had to be all or nothing. The territory of the Gokturks certainly has some land suitable for agriculture, but not that much. So, would it be possible to have a situation where some of the Gokturks sedentarize while others retain their nomadic lifestyle? Perhaps there could even be a system where some clans spend a certain number of years looking over agricultural fields and then an equal number of years roaming the plains as nomads, thus allowing them to always retain enough people with knonwledge of how to thrive in either lifestyle?
If this works, it could possibly allow the Gokturks to sustain a larger population and have stronger institutions while still being able to keep a large, cavalry-based military that can live of the land, thus retaining much of their advantage over their neighbours.
What would be the consequences of a buddhist and at least partially sedentary Second Turkic Khaganate? Could they hold on to their territory in central and East Asia? Could they expand it in one or several directions? How would their society and culture evolve if they persist in the long term as an empire in close contact with the Sinosphere?