And I have a possible academic founding, that I really want to discuss with you. I believe that the rise of the Abbasid dynasty was partly relating to the confrontation between the Tang dynasty and the Second Turkish Empire. And I will explain

The eastern Turks got back their independence in the year 683, they set up the second Turkish empire, and it confronted with china for decades, and China really wanted to destroy the empire. But Turkish empire had two allies, the first one was the Kitan Tribes, at the left flank of the Turks, the another one was Solu, the chief of the Turgesh khanate ( he married his daughter to the Khan of the Second Turkish empire), which was at the right flank

And according to the Chinese historical sources, Tang emperor of, Xuánzōng , attacked the Kitan and the Turgesh, in order to encircle and isolate the Second Turkish Empire, and Solu was defeated , he was killed by his pro Chinese general. And China completed her encirclement over the Second Turkish Empire.

We knew that this empire was mainly built up by the Arabian army of the Khorasan province, and before they rose up against the Umayyad dynasty, the Khorasan army tried to conquer the Transoxiana, those rich oasis states at this region got help from Solu and the Turgesh tribe( even from China, but tang only “helped” them through beautiful political words), and Solu and his Turgesh warriors defeated the Khorasan army for several times.

But now Solu was dead, the turgesh tribe warriors fought against each other in a bloody civil war, the oasis lost the protector, the Arabian Khorasan attacked and conquered those oasis city states, and of course, we could imagine, the Khorasan army got a large amount of wealth from the city states, this Khorasan province became rich, and the Khorasan army became powerful, now they were rich, they were in a high morale, they had a very safe backyard(the Turgesh was no longer a threat), and they also had a high prestige in the Arabian Empire( the wars of the other front did not go well, the Arabs were repulsed by the Franks and the eastern Roman at the same period).

And the Khorasan was a remote frontier province, the Umayyad had expelled a large amount of the political rivalries to the province, the army had a strong anti Umayyad fraction, and now they were rich, strong, an d in a high morale, so it was the time to build up a new dynasty, and they defeated the Umayyad and built the Abbassid

So could we conclude that, if there were no Chinese-Turkish confrontation, Chinese might not want to overthrow Solu, and the latter would fight against the Khorasan army, and protecting the Transoxiana city states, then it was hard for the Khorasan army to carry out their conquer, and it was also harder for them to rise up again the Umayyad dynasty, since the army did not not have the wealth, morale and prestige to do so, only the dead of Solu, let the Khorasan army to conquer the Transoxiana city states, and with conquest, the anti Umayyad Khorasan army had the mean to overthrow the old dynasty, and built up the Abbassid dynaasty

So I conclude the confrontation between the Tang dynasty and the Second Turkish empire had a influence on the rise of the Abbassid dynasty