generally believed that the calendar in that period was still based on the <i>s&#236;f&#275;n</i> system. It is also clear from the excavated calendar table, as well as historical documents, that the month order of the calendar at that time was the same as the Zhuanxu calendar, in which the first month of a year began with month 10, followed by month 11, month 12, month 1, ..., month 9. A leap month was placed at the end of a year after month 9 and was called post month 9 (&#24460;&#20061;&#26376;). The pro