The Qin are one of the alien races present in the Trinity Universe, and nominally allies of Earth. Their homeworld is Qinshui. Both names were given by the Chinese explorers who made first contact, based on their perceived similarity to the costumes used in a particular genre of Chinese opera.
The Qin in their natural state are three-foot-long, slug-like beings. However, their mastery of biotech is so complete that they easily create humanoid shells for themselves out of a crystalline substance, the better to interact with humans. They keep their true form a closely guarded secret even from the human embassy on Qinshui.
The Qin have shared much of their technology with humans; thanks to them, terraforming Mars is expected to take about 75 years rather than the millenium Orgotek originally estimated.