What are the aspects of the prosperity of Dunhuang case art in Tang Dynasty?

The Tang Dynasty is the mature period of Dunhuang pattern development, which is rich in content and exquisite in art, surpassing the previous generation. Among the more than 200 Tang Dynasty grottoes in Dunhuang, each grotto has a different pattern, with various patterns, bright colors and rich and gorgeous lines. The overall atmosphere is warm and harmonious, showing a scene of joy, peace and happiness. The early Tang patterns in the grottoes are simple in graphic structure, beautiful and lively, and brightly colored; During the prosperous Tang Dynasty, the designs of grottoes were mostly composed of lotus flowers, side decorations and some hanging curtains. Lotus is gorgeous and rich, with rolling grass, flowers and semi-flowers as the main side ornaments, while hanging curtains are relatively simple, mainly enriched by flowers filled inside and flying grass. The design of grottoes in the middle Tang Dynasty is another development peak after the prosperous Tang Dynasty, represented by tea patterns, auspicious birds and animals, algae wells, round lamps and side decorations, with rich and gorgeous contents; The design of the grottoes in the late Tang Dynasty is basically a continuation of the design in the middle Tang Dynasty, which continues the grand and spacious features in the scene, but it lacks interest and artistic conception in the content and gradually moves towards stylization ~