Back then small characters were carved into tortoiseshells to record divinations, keep accounts, and list the ingredients of herbal medicines. A piece 0.9 cm wide and 15 cm long with 20 characters written on it has been found from the Warring States era (475-221 BC). This could be regarded as the forerunner of miniature books in East Asia.
當時龜殼上以極小字體記載藥方、占卜和帳目等資料；戰國時代則發現，在寬僅 0.9cm、長 15cm 的竹簡上寫了 20 多個字，可說是東方微書文化的先驅。