The reasons why pepper was used to paint the walls in ancient times:

1. Because the Zanthoxylum bungeanum tree has many fruits and is a symbol of the reproduction of descendants, the emperor’s wives and concubines used Zanthoxylum bungeanum to paint the walls, which was called the pepper house. I hope the princes can be as prosperous as the pepper trees.

2. Paint the walls with pepper for heat preservation.

In the Han Dynasty, there was a greenhouse hall in the palace. Zanthoxylum bungeanum was used as insulation material for the mud room. Brocade tapestries were hung, fire screens were set up, curtains were made of wild goose feathers, and Western Region blankets were spread on the floor. . You won't feel cold if you stay inside in winter.

The method of using Zanthoxylum bungeanum as an insulation layer was also imitated by later generations.

3. Painting the wall with pepper can prevent moths.

Paint the walls with a powder made from the flowers of the Zanthoxylum bungeanum tree. The color is pink. It has an aromatic smell and can protect the wooden structure of the palace and has the effect of preventing moths.

Extended information:

The building with walls painted with pepper is Jiaofangdian.

Jiaofang Hall is located in Chang'an City, the capital of the Western Han Dynasty. It belongs to the Weiyang Palace complex and is the residence of the queen. Queens such as Zhang Yan, Dou Yifang, Chen Ajiao, Wei Zifu, etc. lived in Jiaofang Hall of Weiyang Palace.

It is said that Queen Dou of Dou Yifang often rested in the Jiaofang Hall when she was alive. It was also because the pepper powder on the wall was good for people, so Queen Dou lived for a long time and was in good health. He also did a lot for his husband Emperor Hanwen and his son Emperor Hanjing.

The Greenhouse Hall appeared in the Han Dynasty. There were various cold-proof measures and equipment in the hall, such as coating the walls with pepper and mud, so it was called "Jiaofang Hall". During the reign of Emperor Gaozu of the Han Dynasty, Jiaofang Hall was the queen's palace, so "Jiaofang" became the nickname for the queen.

The main hall of Jiaofang Hall faces north and south, with double ques in front of the hall. It is very rare to have a palace in front of the palace, which is beyond the scope of ordinary palaces. It shows the high architectural standards of Jiaofangdian.

People's Daily Online - The emperors of the Han Dynasty were luxurious in keeping out the cold: Zanthoxylum bungeanum was used to insulate the room and wild goose feathers were used as curtains

Baidu Encyclopedia - Zanthoxylum bungeanum

Baidu Encyclopedia - Jiaofangdian