Walls at that time already used dirt mixed with grass, or else mud, or even construction materials like lime. This type of wall construction was maintained for a long time, and it was only in the Western Han dynasty, about 2000 years ago, that brick was used for construction.
當時的牆面，已是以土拌草或泥，甚至運用石灰等建築材料，這樣的土牆建築一直維持很長一段時間，到距今兩千多年左右的西漢時代，才有磚造建築。