China, Eastern Zhou Dynasty-Warring States Period. State of Y n. Ca. 400-220 B.C. AE "Ming" knife money (140x16 mm, 15.03 g). Yi Dao in early zhuànsh Hànzì (seal script) characters.
From David Tranbarger: This type of knife money takes it's name from the eye-shaped character on the obverse which has traditionally been interpreted as ming. An alternate reading is yi and according to Hartill (p.63) a mint for Ming knives has been found at Xiadu to the southwest of Beijing. This was the ancient site of Yi, the capital of the State of Yan in the 4th century BC. The coins themselves have been found widely throughout China and even in Korea and Japan.