What is a dragon embracing a tiger?

On the left of the gate is Qinglong, and on the right is White Tiger. Qinglong was originally the God of the East in ancient mythology, and one of the Seven Hosts and Four Elephants in the East in Taoism. Twenty-eight lodging houses, and seven lodging houses in the East (Jiao, Kang, Bian, Fang, Xin, Wei and Fan) have the image of dragons, which are located in the East, belong to wood and are blue in color, collectively called Qinglong, also known as Black Dragon. The forty-four volumes of Taizhi call Qinglong Dongdou as follows: "Jiao Su Tianmen, Kang Su Ting, Chang Su Tianfu, Su Fang Tian Yi Xing Jun, Xin Su Uranus Jun, Wei Su Tian Ji Xing Jun, Ji Su Tian Lu Xing Jun." As for its image, there are seven clouds in The Collection of Doors and Tongjiao: "Oriental Dragon Horn, full of pride, spits clouds and glows, thunders, flies to octupole, walks around the four ghosts and stands on my left. In addition, Taoism also uses it in alchemy. For example, Volume 72 of "Seven Chapters of Clouds" quotes the Dan of the four ancient gods, saying: The dragon is a dragon, and the oriental wood is also mercury. It is clear and unwilling, not turbid, not desirable, far away, and infinitely hidden, so it is called dragon. The white tiger was originally the western god in ancient mythology, and it was one of the four images of the seven Pleiades in Taoism. The seven western lodgings (Kui, Lou, Stomach, Ang, Bi, tapir and Shen) in the twenty-eight lodgings are elephant tigers, located in the west, belonging to gold and white in color, which are collectively called white tigers. In Volume 44 of Emperor Tai Shang Ru Zhai Yi, White Tiger Xi said: "Su Kui Tian Jiang Xing Jun, Lou Su Tian Prison, Su Wei Tian Cang Xing Jun, Angsu Tianmu Xing Jun, Bi Su Tian Er Xing Jun, Li Su Tianping Xing Jun, Shen Su Tian Shui Xing Jun". As for its image, the book "Daomen Tongjiao Need to Use Collection" has seven clouds: "West should be a tiger, with the quality of Ying Ying, and the tone should be fixed. "At the same time, Taoism also uses it in alchemy. For example, Volume 72 of Yun Qi Tanabata quoted the Dan of the Four Gods in ancient books and said, "White Tiger, Xijin, also got a real job. "Jing" says: if a son succeeds, his wife has a different name, and the five elements are born together, which is also exquisite. It can't move, so it's called a tiger.