Tangniu mutton is a unique and famous snack in Xi 'an Anfangbang. Xi 'an Laosunjia Restaurant has been open since 1898, and has a history of one hundred years.
Legend has it that beef mutton soup evolved from the ancient "beef mutton soup" in 1 1 century BC. In the Western Zhou Dynasty, "beef and sheep soup" was listed as a "gift" for kings and princes. According to the Book of Song Dynasty, in the Northern and Southern Dynasties, Mao Xiu presented delicious soup of cattle and sheep to Song Wudi, and Emperor Wu was made an official history, and later he was promoted to Doctor Guanglu, a famous scholar. There is also a funny legend that Zhao Kuangyin, the emperor of the Song Dynasty, was trapped in Chang 'an before he proclaimed himself emperor and lived a life of starvation all day. One day, he came to a shop where beef and mutton were being cooked. The shopkeeper felt sorry for him, so he let him break up his dry steamed buns, then poured him a spoonful of hot soup and cooked it thoroughly on the fire. Zhao Kuangyin wolfed down his food and thought it was the best food in the world. Later, Zhao Kuangyin put on a yellow robe and became an emperor. One day, he passed by Chang 'an, and he still remembered the steamed buns of beef and mutton he had eaten here in those years. Wu specially found this store to eat beef and mutton bread in soup, which was still delicious, even better than delicacies, and rewarded the shopkeeper of this store. Once the story of the emperor eating steamed buns spread, beef and mutton became a famous snack on Chang 'an Avenue. Su Dongpo, a great writer in the Northern Song Dynasty, once wrote a poem of praise, "There is bear wax in the dragon's stomach, and Qin only cooks mutton soup."