In ancient times, there was no ice-making technology. In ancient times, wealthy families and royal families had special ice rooms to store ice cubes. When it freezes in the icy river, they ordered people to collect ice cubes for summer use. In hot summer, ice cubes are needed to cool off the heat.

The custom of picking ice in cold weather lasted from Shang and Zhou Dynasties to Ming and Qing Dynasties. The Zhou dynasty picked ice at the beginning of the twelfth lunar month, and the Ming and Qing dynasties picked ice three or nine days before and after the great cold. According to the "Yanjing Times" written by Fu Cha Dunchong in Qing Dynasty, "it is difficult to meet March 9 in winter. When it is chiseled at night, it sounds like stone, which is called ice. After March 9, although ice is hard to use. " As the saying goes, "the cold is in the March 9th", and it is the hardest to freeze at this time, which is in line with the requirements of the royal family. Wang Yongbin, a late Beijing-based expert on literature and history, said, "Breaking the ice in three or nine days"; If you hit a layer, the water will soon freeze again. If you hit it again, it will freeze again. You can hit it three times. By the fourth crop, the thickness and hardness of the ice were not enough, so I stopped playing.