中国为什么要以鼠年开始纪念年份?【用英语回答o】

It is a Chinese tradition. Every twelve years is a circle and for each year in a circle, an animal is named to the year. According to a fair tale, all animals were participated in a race to decide their ranks in the circle. The mouse won the race as the first one who reached at the destination, and the pig was the twelveth. So the year circle begins from mouse and ends by pig.