Бань Гу
From existing literary evidence, commoner categories in China were employed for the first time during the Warring States period (403–221 BC). Despite this, Eastern-Han (AD 25–220) historian Ban Gu (AD 32–92) asserted in his "Book of Han" that the four occupations for commoners had existed in the Western Zhou (c. 1050–771 BC) era, which he considered a golden age. However, it is now known that the classification of four occupations as Ban Gu understood it did not exist until the 2nd century BC. Ban explained the social hierarchy of each group in descending order: