The first dated Chinese new year celebration can be traced back to Warring States period (475 BC – 221 AD). In "Lüshi Chunqiu", a exorcistic ritual called "Big Nuo (大儺)" was recorded being carried out in the ending day of a year to expel illness in Qin (state). Later, after Qin unified China and the Qin dynasty was founded, the ritual was continued. It evolved to cleaning up houses thoroughly in the preceding days of Chinese New Year.