How did niu geng 牛耕 (cattle plowing) develop in East Asia? This is not an easy problem to solve. Niu geng, also known as li geng 犁耕 (plowing), developed step by step from ou geng 耦耕 (pair plowing with lei si 耒耜 as a tool). If we do not know what kind of material lei si is made of, why do we need two people to work together for ou geng, and the domestication of cattle in East Asia. We would not understand the origin of niu geng.