How were burned and sun-dried bricks used in the Great Wall of China?

The Great Wall of China was constructed using a variety of materials that evolved based on regional availability and the needs of different dynasties. While the wall is often associated with stone and rammed earth, both burned and sun-dried bricks were utilized in its construction.12

In the western desert regions, the wall was primarily a simple structure composed of rammed earth and adobe (sun-dried) bricks. In other areas, the wall incorporated a mixture of brick and stone. By the time of the Ming dynasty, which produced the most well-preserved sections, the use of more durable materials became more prominent. Although fired brick was widely used in Chinese building technology to set high standards of quality, the specific application of burned versus sun-dried bricks varied significantly across the wall's vast length to accommodate the rugged terrain and local resources.13