In the early years, the four seas were unified and the world was at peace, and neighboring countries all paid tribute to China. A northern country was unconvinced and wanted to play a trick on China people, so it presented five cars of yam eggs. It was made in the court at that time. It was delicious, but it was uncomfortable to eat. The king issued a decree to distribute these yams outside the Great Wall to relieve the Lebanese people. After eating it, people feel uncomfortable, so they use yam eggs to send beggars away; Beggars don't want to eat either, but they are hungry and can't eat. The beggar leader in Zhangjiakou made up a jingle to let the brothers sing when begging for food: "Auntie, Auntie, give me something to eat. Never give yam eggs. If they don't cook properly, they will get into trouble. "

Although beggars don't want to eat yam eggs, they are very hungry and have to eat them. The light person has an upset stomach, and the heavy person dies. One day, the beggar's head was poisoned and tortured to death. His brother looked for doctors and medicines everywhere, but to no avail. At this time, an old woman with gray hair brought a bag of bluish-white medicine. The beggar was much better after drinking some potions. The old woman also told the beggar, "This medicine is Daqing salt produced in Qinghai Lake. When cooking yam, put some salt, which is delicious and won't upset your stomach. " After that, the old woman stamped her feet and rose into the air in the wind, becoming the appearance of Guanyin Bodhisattva. The beggar leader hurriedly kowtowed in the air with the beggar, thanking Guanyin Bodhisattva for saving his life.

Since then, people in Zhangjiakou have dared to eat yam eggs. Because yam adapts to the growth in the north, it has short maturity, drought tolerance and high yield. Since then, yam has been planted on a large scale in this area.