When you visit traditional houses, old buildings and temples in China, Taiwan and Hong Kong, you are likely to see posters tacked on the doors of the front entrances, which depict either fierce-looking warriors, mythical animals or deities. These are the illustrations of Men Shen or the Gods of Entryways. This term do not refer specifically to any deities, rather it describes the role of a group of deities that safeguard homes and premises.
There are two types of deities that serve as Men Shen, the peaceful deities and the wrathful deities. The peaceful deities are mostly celestial beings that have kind and gentle appearances. They work to pacify instead of forcefully casting off evil spirits and negative energies, as the wrathful deities would. The wrathful deities have fearsome appearances and may take the form of an animal like a tiger, or the form of human. In human form, they are usually legendary figures like Zhong Kui or Qin Qiong and Jing De.
Zhong Kui is a famous folkloric ghost vanquisher and is a popular choice of Men Shen for entrances with single door pane, while Qin Qiong and Jing De is commonly used for double-pane doors.
According to the folklore, during the Tang Dynasty (around 630 A.D.), the Emperor Taizong was beset by demons that howled outside of his chamber every night. Upon hearing the trouble of the emperor, the two generals Qin Qiong and Jing De offered to guard the entrance of the emperor's chamber at night. With the presence of the generals, the demons no longer have the temerity to approach the emperor's chamber. However, the generals would not be able to continually guard the doors. So the emperor ordered an artist to paint the images of the two generals and posted them at the palace gate to trick the demons into thinking that the generals were still guarding the doors. Of course, it worked. Ever since, Qin Qiong and Jing De became the most eminent form of Gods of Entryways.
The form of the Gods of Entryways varied according to the folklores and beliefs of the era, as well as the geographical regions of which it is used. Nonetheless, the use of amulet at the front doors to keep homes safe may be traced back to the Han Dynasty (206 B.C.–220 A.D.) and possibly earlier. At that time, the front entrance amulets were called "Peach Plank". The ancient people would literally hang a piece of plank made from peach wood at the front entrance because it was believed that peach wood has the ability to ward off evil spirits. Every year, when the spring festival approaches, people would find themselves a good piece of peach wood and then decorate the wood by engraving auspicious words or images on it. This custom continued but the planks were superseded by papers.