More than 30,000 years ago, Chinese ancestors invented the 10 Tian Gan(or heavenly stems)and 12 Di Zhi(or 12 earthly branches for chronological purpose.
More than 30,000 years ago, Chinese ancestors invented the 10 Tian Gan(or heavenly stems)and 12 Di Zhi(or 12 earthly branches for chronological purpose.
3万多年前，中国的祖先发明了10天干和12地支（按时间顺序排列）。