Qin, Qín or Ch'in (Wade-Giles) can refer to...

A state:

• Qin (state), a state of China during the Spring and Autumn and Warring States Periods of the Eastern Zhou Dynasty.
• Qin Dynasty, which followed Qin's unification of China
• The Former Qin (Di), Later Qin (Qiang) and Western Qin (Xianbei) in the Sixteen Kingdoms period.

Others:

• King Qin, a title of the Emperor Tang Taizong of China
• 秦, or Qín, an abbreviation for the Shaanxi province of the People's Republic of China
• a kind of musical instrument of China, also known as Guqin or Gu Qin (old Qin).

See also: Daqin