Qinglong

In Chinese astrology, the “Blue Dragon” are known as the “Azure Dragon” or the “Blue Green Dragon” as in Mandarin, it’s name is is 青龙 (Qīnglóng). The Azure dragon is a very important creature and symbol in Chinese myths and culture, as such it represents a few things. As exlained by another wonderfully written answer, the Azure Dragon is one of the Four Symbols, which are Chinese constellations, and the other three are the White Tiger (白虎), Black Turtle (玄武), and Vermillion Bird (朱雀). The Azure Dragon represents springtime and the east. He also appears on the flag of the Qing Dynasty.

The Azure Dragon, in stories and myths is also one of Four Dragon Kings, known in Mandarin as 四海龍王 (Sìhai Lóngwáng). They are deities of water, winds, rain, floods, weather, storms, and oceans. They represent the four cardinal directions, four seaons, and the four body of waters that border China. The Four Dragon Kings are:

Ao Guang 敖廣 (Áo guang), Dragon King of the East Sea
Color: Azure Dragon 青龙 (Qīnglóng)
Patron God of the East China Sea
Springtime

Ao Qin 敖欽 (Áo qīn), Dragon King of the South Sea
Color: Red Dragon 赤龍 (Chìlóng)
Patron God of the South China Sea
Summer

Ao Shun 敖順 (Áo shùn) or Ao Ming 敖明 (Áo míng), Dragon King of the North Sea
Color: Black Dragon 黑龍 (Hēilóng)
Patron God of Lake Baikal
Winter

Ao Run 敖閏 (Áo rùn) or Ao Jun 敖君 (Áo jūn), Dragon King of the West Sea
Color: White Dragon 白龍 (Báilóng)
Patron God of Qinghai Lake
Autumn

The Azure Dragon as the character and deity Ao Guang has appeared in stories like Journey to the West where he gave armor, shoes, and a phoenix-feathered cap to the Monkey King Sun Wukong. He also appeared in another story called Investiture of the Gods, or Fengshen Yanyi, as a fearsome deity who demanded child sacrifices from a nearby village, and thus had to be stopped by the boy hero Nezha.

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