Due to the establishment of Chang'an, the capital of the Zhou, Han and Tang dynasties, Shaanxi has formed a national political, economic and cultural activity center very early. Therefore, the exotic flowers and fruits of the Quartet have also been introduced and cultivated. During the period of Emperor Wu of the Han Dynasty, the cultivation of fruit trees in Shaanxi entered its peak. The "Xijing Miscellanies" describes the fruit tree varieties of Shanglinyuan: "The group of ministers and distant fruits are dedicated to fruit trees... pear ten... jujube seven... Lisi four... peach ten... Li fifteen... 柰 three... plum Seven...Apricot II", which also records "... 柰 three, white peony, purple 柰 (flower purple), green 柰 (flower green)", that is, small apple or cotton apple. It is the same as the western apple that is cultivated now. After the Tang and Song Dynasties, sand fruit, honey fruit, red apple and white apple have been planted in Guanzhong and Shaanxi folk courtyards in Shaanxi. At present, the sea otters produced in Shenmu, Fugu and other places in Shaanxi have a wide variety and are widely distributed, and some have not yet left the original state.