Traditionally, these served both as road signs and as a means for passersby to leave messages, emerging during the remote Yao and Shun era of the primitive society. At that time, people would set up a wooden post along major thoroughfares to identify the path and act as a marker. Later, post stations and relay stations also used it for identification. It was known as "Huanmu" or "Biaomu," later collectively referred to as "Huanmu." Since the ancient "Huan" sounds similar to "Hua," it was gradually pronounced as "Hua." On this wooden post, travelers could carve their opinions, hence it was also called "Bao Mu" or "Fei Bao Mu." The term "fei bao" in ancient times meant discussing right and wrong, akin to modern-day feedback. Therefore, it also served as a modern-day "suggestion box." Historical records indicate that during Yao's time, the "fei bao mu" were marked with horizontal wooden bars.