What do you mean by left Qinglong and right White Tiger?

Among the many door gods, there is a special door god, which is specially used to guard the mountain gate of Taoist temple. They are the "left green dragon, right white tiger" that Taoism often says. Usually, the left green dragon and the right white tiger represent the left and right positions, not the real green dragon and white tiger.

In ancient times, China established twenty-eight lodges, which were divided into four groups with seven stars in each group. These four groups are the stars of the sky in spring, summer, autumn and winter.

each season is equipped with an animal and an orientation (see attached figure).

Spring is matched with the East, and its spiritual object is Qinglong, because Qinglong represents the vitality of spring and the growth of all things. The vitality of [Qinglong] is equivalent to the budding of flowers and plants in spring. As for summer, the weather is hot, so it is represented by red fire.

Moreover, in summer, birds are particularly active, so the spirit of summer is Suzaku. Suzaku is a red fire finch. In addition, summer is accompanied by the south.

Autumn is full of cold air, and there were more executions in ancient times than autumn, which is called autumn decision. And when autumn comes, the yellow leaves of trees fall. So [White Tiger] just represents the lonely and cold atmosphere in autumn. Autumn is accompanied by the west.

winter is accompanied by the north. In winter, flowers and trees no longer flourish, and animals hibernate, which is like a collection. Therefore, Xuanwu just represents this season. The so-called [Xuanwu] is a big black turtle, because turtles have a collection image. Black represents convergence.

Qinglong: Qinglong is one of the four elephants in the traditional culture of China. According to the Five Elements Theory, it is a spirit beast representing the East. Qinglong is both a name and a race, and its orientation is east and right, representing spring.

among the 28 constellations, Qinglong is the general name of the seven eastern stars (horn, sonority, mutuality, room, heart, tail and dustpan). The Seven Hostels in the East are also called black dragon, and the Seven Hostels in the East in black dragon-Jiao, Kang, Bian, Fang, Xin, Wei and Ji, which are very dragon-shaped. From their word meaning, we can see that Jiao is the angle of the dragon, Kang is the neck, Bian is the root of the neck, and Fang is the arm, the threat and the shoulder.

White Tiger:

The white tiger is one of the four elephants in China traditional culture. According to the Five Elements Theory, it is a spirit beast representing the West, and the season is autumn.

among the 28 stars, the white tiger is the general name of the seven western nights (Kui, Lou, Wei, Ang, Bi, Gou and Shen). Its image tiger, located in the west, belongs to gold and white, and is generally called white tiger.

Reference: Baidu Encyclopedia-Zuo Qinglong You Bai Hu