baked bricks of regular shape began to be employed for vaulting underground tombs. Hollow brick tomb chambers rose in popularity as builders were forced to adapt due to a lack of readily available wood or stone. The oldest extant brick building above ground is possibly Songyue Pagoda, dated to 523 AD.

By the end of the third century BC in China, both hollow and small bricks were available for use in building walls and ceilings. Fired bricks were first mass-produced during the construction of the