According to legend, during the Warring States Period, Ying Zheng, king of Qin, led his troops to fight day and night, often without drinking water or eating rice for several days. One day I arrived at the southern foot of the Qinling Mountains, which is the sunny side of the mountain. The king of Qin saw an old man hanging a row of noodles as thin as hair in a roadside farmhouse, and his appetite was big enough for him to cook. The old man quickly cooked noodles and presented a big bowl of peasant sauerkraut soup. After Qin Shihuang ate it, he felt sour, fragrant, slippery, refreshing and delicious. When asked, the old man replied that it was handmade noodles, because the shape of noodles was "long and thin", so it was also called "longevity noodles". Qin Shihuang was overjoyed and rewarded the old man. Since then, local officials have paid tribute to the court year after year and have been listed as the best products of royal health care.