The majority of farm houses and barns in China are built with home-made sun-dried mud-and-straw bricks. They are stacked up using wet mud for the mortar (thus the origin of the contemporary contractor's term "mud" for mortar). By employing string levels a remarkably rigid, straight, and durable building can be made from earth. But in Yunnan I saw how the locals use small bamboo twigs as a type of rebar. They lay these very strong sticks (bamboo has a tensile strength similar to steel) along one course of bricks every tenth row or so, just as we might add rebar in wet cement. The bamboo serves the same purpose and its use probably predates rebar and concrete.