The terracotta army was discovered by accident in 1974 at Xian, in China. It contains thousands of terracotta figures depicting the armies of Qin Shi Huang, the first Emperor of China. The Terracotta Army was constructed to accompany the Emperor as an afterlife guard. Previous Emperors had servants etc, executed and put in their graves with them.
A recent BBC programme posed an interesting theory that Greek artists were brought to China to sculpt the army because Chinese sculpture of the time was quite crude, and they would not have had the expertise to produce such astounding reproductions of the army, particularly the individual faces.
However I suggest a much simpler explanation of how these particular Chinese sculptures were elevated from crude images, to those of the stunning faces shown on the Terracotta Army.
We know that the army was assembled from precast sections one of which was the head.
The fact that so many of the heads of the army show closed eyes supports my theory that they were made from clay masks placed on the head to take an impression. Straws could have been put in place to allow the person to breathe whilst the impression was taken. This would have been a relatively quick and simple operation to carry out with minimal sculpting work required.
Use clay to take an impression, bake the clay to use as the mould for the terracotta clay head. Sculpt other features onto the head, such as the caps and ears and if necessary fill the hole left by the straws used for breathing.
After baking assemble the head onto the body mould. It seems there were number of ‘Standard’ mouldings made to resemble the relevant uniforms.