Original sentence: Before that date, a variety of coins were used in China, usually in the form of blades (knife money) or other implements, though round coins with square holes were used by the state of Zhou before it was extinguished by Qin in 249 B
Edited sentence: Before that date, a variety of coins were used in China, usually in the form of blades (knife money) or other implements, though round coins with square holes were used by the state of Zhou before it was extinguished by Qin in 249 BCE