The finding shows that a highly sophisticated arithmetic had been established for both theoretical and commercial purposes in ancient China.
The bamboo strips, which date back to the Warring States period (475-221 BC) before the unification of China, were donated to Tsinghua University in Beijing five years ago. However, it was not known at the time what was written on the strips because they arrived muddy and covered in mould. It is suspected that they originated from the illegal excavation of a tomb, and the donor had purchased them at a Hong Kong market.
Once the strips had been carefully cleaned, it was found that they contained vertical lines of ancient Chinese calligraphy painted in black ink. However, assembling the pieces was like piecing together a very difficult jigsaw puzzle.