In which country was the Chu-ko-nu repeating crossbow invented?

The repeating crossbow is a Chinese crossbow that was invented during the Warring States period, and remained in use until the late Qing dynasty. It is also known as the Zhuge crossbow (romanized Chu-ko-nu) due to its association with the Three Kingdoms-era strategist Zhuge Liang (181–234 AD).

According to the Wu-Yue Chunqiu (history of the Wu-Yue War), written in the Eastern Han dynasty, the repeating crossbow was invented during the Warring States Period by a Mr. Qin from the State of Chu. This is corroborated by the earliest archaeological evidence of repeating crossbows, which was excavated from a Chu burial site at Tomb 47 at Qinjiazui, Hubei Province, and has been dated to the 4th century BC, during the Warring States Period (475 - 220 BC).

Unlike repeating crossbows of later eras, the ancient double shot repeating crossbow uses a pistol grip and a rear pulling mechanism for arming. The Ming repeating crossbow uses an arming mechanism which requires its user to push a rear lever upwards and downwards back and forth. Although handheld repeating crossbows were generally weak and required additional poison, probably aconite, for lethality, much larger mounted versions appeared during the Ming dynasty.