According to legend, when Emperor Qianlong of Qing Dynasty visited Hangzhou, he tasted Longjing tea and was full of praise. He ordered people to choose tea in Longjing Mountain area. In order to prevent sky-high prices, the emperor specially presented "Eighteen Imperial teas" to local villagers to ensure the quality and production technology of Longjing tea. This 18 tea plant was named "before rain" and "before valley" respectively, and grew in Longjing Mountain area.
Today, Longjing Mountain, where eighteen tea trees are located, has become a tourist attraction. Every spring and autumn tea picking season, thousands of tourists come to taste and buy these high-grade Longjing teas. Eighteen kinds of imperial tea have also become the representative of Longjing tea, which is recognized as the best in Longjing tea.