 These pit houses were sited for solar gain by aligning the door to the "Yingshi" (, or simply "shi" ) asterism just after the winter solstice.Already, at this early stage the principle of south-facing entry was firmly established.As in other Neolithic communities, life at Banpo was synchronized to the agricultural year, which was timed by the movement of the Big Dipper, which functioned as a celestial clock.