This is one of the set of 4 paintings that are very rare with two characeteristics that make them unique.
First, the blue background is seen only in a handful of Yao ceremonial paintings. These are highly prized finds for their rarity as well as their aesthetic value.
Second, the painting style is very unique - there are characters on a plain background without any embellishment of the background. These are works of 'naive' art. It could be that he had not yet come within the folds of influence of the styles that were popular elsewhere and his personal style remained uncorrupted by the 'popular' view. As a result the artist we see the stamp of his own soul on the painting, rather than just that of his ethnic group. And it is this soul-stamp that makes this set of 4 pieces extremely charming.
This folk rendering of the Palace of the Grand Pure One demonstrates the strain of Daoism which binds with Buddhism. These paintings come in sets of three with the other two being The Palace of the Supreme Pure One and the Palace of the Jade Pure One. Collectively, these are the highest deities in the Dao pantheon. Collectively, these are the Three Pure Ones who are responsible for creation. In this representation we find the Bodhisattva Samantabhadra, linked to great vows and action. Beside him is his steed, a white elephant.
The piece comes from the north of Vietnam from ethnic minorities (Yao, Tay, Nung, Cao Lan, San Chi) whose belief system often mixes Daoism with elements of Buddhism, Confucianism and animism.
There is age related wear and fading.