During the build up to Chinese New Year Door Gods are placed on the external doors of houses. This is an age of tradition dating back to the Tang Dynasty (618 - 907 AD). The Emperor Taizong is said to have fallen ill, and had a dream in which ghosts came to the palace in search for him. He recounted this tale to his officials the next day, and the story quickly spread through the Imperial Court: such matters were not taken lightly. The emperors top two generals, Qin Qiong and Yuchi Gong, both of whom had fought to establish the Tang dynasty stood guard outside the emperor's bedroom door.
The emperor slept soundly in the knowledge that he was protected by these two generals, and had no further dreams of the ghosts. However, after a few nights the emperor became concerned for the generals. He ordered that two paintings be made, one of each general. Once completed, the emperor had these hung on the door to his room, and relieved the generals.
This tale soon became widely known, and in their eagerness to share the protection of these "Door Gods" the common people made their own paintings and placed them on their doors. The tradition has continued ever since.