The historical Qin dynasty of China ended in 207–206 BCE, when its last ruler Ziying surrendered and was overthrown, leading into the rise of the Han dynasty.

Because “gin dynasty” is not a recognized historical empire, most people asking “when did the gin dynasty end” are actually referring to the Qin dynasty, whose name in English can sound like “chin” or “gin” depending on accent. If you meant a fictional “Gin Dynasty” (for example from fan works), that family or group is described as still active and therefore has not “ended” in its source material.