People typically seek help from doctors when they experience trouble sleeping and have an unsettled mind.

But when the same problem occurred to Li Shimin, Emperor Taizong of the Tang Dynasty (618-907), the powerful, proud monarch ordered his two most loyal generals, Qin Qiong and Yuchi Jingde, to keep guard outside his palace every night. Sympathizing with their laborious duties, Li later had their painted portraits permanently posted on the palace gates.

Although no one can be sure that this folk tale began the Door Gods custom, it somehow became a New Year tradition: having the paintings of the two standing generals — indeed, real historical figures — on doors, which people believed would protect them from evil spirits and usher in a blessed year.

Other figures, both real and fictional, who represent strength, bravery, or integrity, such as Guan Yu and Zhang Fei, two generals who fought side by side in the Three Kingdoms (220-280), were also favored candidates for hanging Door Gods at Chinese New Year.

The unique Door Gods tradition is one of many diverse, radiant folk arts that feature vivid, auspicious motifs still popular today, such as animals, historical figures and patterns.

More than 40 selected examples of this customary variety are on show until Sunday in the Vivid and Vibrant: Auspicious Imagery in Chinese Folk Art exhibition at the National Art Museum of China in Beijing. While it offers glimpses into the museum's rich collection of folk handicrafts, it unfolds a vigorous panorama of creative grassroots aesthetics — people farming in the fields or chatting after work — that have been passed down through the centuries.