During the height of the Tang Dynasty in Chang'an (modern Xi'an, China), Chinese military metalworkers perfected 'shanwenkai,' or mountain-scale armor. This advanced protection used interlocking, Y-shaped iron pieces woven directly together without rivets or visible cords, creating a flexible mesh that looked like a field of Chinese characters for 'mountain.' This structural layout offered outstanding defense against crossbow bolts and sabers, becoming the signature armor for elite Tang commanders.

The gleaming, geometric beauty of mountain-scale armor deeply permeated Tang Dynasty poetry. Masters like Li Bai and Du Fu wrote numerous verses depicting the harsh realities of frontier warfare, frequently utilizing images of 'iron garments' and 'shining scale armor' frosting over in the cold desert winds.