The Mongolian and First Qin Dynasty.

This will be unique among all the long series of Chinese Dynasty.
It is different as Chinese NEVER consider the mongol as thier own.
Thie always belong to the Babaric Tribal Council no matter how big thier empire and sharp thier arrow.
The mongul did not adopt the Mandarin System during the Yuan Dynasty.
So it is a short live one  and ended in one hundred years.
Perhaps the only good thing is the visit of Marco Polo from the other end of the M empire. Bringing along some Culture exchange and early global trade. ( but Ancient Chinese Emperor alway s feels the Middle Kingdom ahs everything, so Trade is Not the Top agenda)

The First Qin Dynasty is also unque .
As it is over Centralised and over Militarise even to Chinese Standard.
The Chinese Norm is Benevolent Rule ( Ren Zheng) as administer as the Prime Minister ( Zhai Xiang).
There is still many debate about the "Rightness" of the Qin Shi Emperor. Although Unity and system of Chinese Rule are establish by Him.
Most Chinese afiliated them as the HAN People of the 2nd dynasty.