Master Mao Senior (Da Mao Gong 大毛公) and Master Mao Junior (Xiao Mao Gong 小毛公) were both Confucian scholars, the former living during the late Warring States period 戰國 (5th cent.-221 BCE), the latter during the early Former Han period 前漢 (206 BCE-8 CE).
Mao Senior, personal name Mao Heng 毛亨, hailed from the region of Lu 魯 (modern Qufu 曲阜, Shandong) or Hejian 河間 (modern Nanxian 南縣, Hebei) and studied the Shijing 詩經 "Book of Songs" with the philosopher Xunzi 荀子. He stood in the line of Confucius' disciple Zixia 子夏 and wrote down his interpretation of the Shijing in the book Maoshi guxun zhuan 毛詩故訓傳 that was transmitted to Mao Chang 毛萇 (Mao Junior). This book belonged to the so-called old-text (or ancient-character) Classics and represents the Mao school of the Shijing (Maoshixue 毛詩學). It was submitted by Mao Chang to Prince Xian of Hexian 河間獻王 and so introduced into the canon of the Confucian Classics tought at the National University.
Mao Chang himself hailed from the region of Zhao 趙 (modern Shanxi) and became an erudite (boshi 博士) of the Mao old-text version of the Shijing that is transmitted until today and therefore also known with the name Maoshi 毛詩.