What do you mean, 79 rivers open and 99 geese come?

The ancient poems written by Jiujiu and Yan Jiujiu are as follows:

/kloc-no shooting in 0/929, on the ice in 3949.

Five nine six nine, watching willows by the river.

Seven or nine rivers open, and nine or nine swallows come.

99 plus 19, plowing cattle everywhere.

Analysis:

1929 It's very cold, so I can't put my hands outside.

The 3949 River is frozen and people can walk on it.

In 5969, the weather turned warmer and trees sprouted.

1979 The river melted, 1989 Swallows flew back from the south.

After 1999, the weather is completely warm and crops can be planted.

The Source and Calculation Method of Jiujiu Songs

Jiujiu Song is a traditional peasant ballad in China. Alias "Jiujiu", also known as "Winter Jiujiu", is a folk solar term in winter in China.

The "number nine" began the day after the "winter solstice" in late February and early February of 65438. When the custom of "counting nine" originated, there is no exact information at present. However, it was popular at least in the Northern and Southern Dynasties. "Liang Chao Shu Jing Chu Chun Qiu" records: "The winter solstice is 998 1 day, which is the end of cold." Count nine cold days, that is, from the solstice of winter, count a "nine" every nine days until the "99" of 81 days, and the weather will warm up.