i found out that it was originally madde from stone, wood, and earth. then later bricks were set up along the wall.

Thats right also the ming dynasty used slaked lime and and sticky rice paste for a mortar.
slaked lime: is made by heating up limestone or taking quick lime and adding water, but that will explode
rammed earth:dirt and and other put between two poles and pushed possess repeated until full, then poles taken away and used for a new section.
sticky rice paste:sticky rice flour and water