The jian (; Cantonese: Gim) is a double-edged straight sword used during the last 2,500 years in China. The first Chinese sources that mention the jian date to the 7th century BCE during the Spring and Autumn Period; one of the earliest specimens being the Sword of Goujian. Historical one-handed versions have blades varying from in length. The weight of an average sword of blade-length would be in a range of approximately 700 to 900 grams (1.5 to 2 pounds). There are also larger two-handed versions used for training by many styles of Chinese martial arts. Professional jian practitioners are referred to as jianke or "swordsmen", a term dating from the Han dynasty.