The Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn period between the 8th and 5th centuries BC.[15] During this time and the subsequent Warring States period, the states of Qin, Wei, Zhao, Qi, Yan and Zhongshan[16][17] all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames.