Traditionally, these served as both road signs and platforms for passersby to leave messages, emerging during the Yao and Shun era of the primitive society. At that time, people would set up a wooden pillar along major traffic routes to identify paths and landmarks. Later, post stations and relay stations also used them for identification, and they were named "Huanmu" or "Biaomu," later collectively referred to as "Huanmu." Because the ancient character "Huan" sounds similar to "Hua," it was gradually pronounced as "Hua." On this wooden pillar, passersby could carve their opinions, hence it was also known as "Bao Mu" or "Fei Bao Mu." The term "fei bao" in ancient times meant discussing right and wrong, akin to modern-day complaints. Thus, it also served a function similar to today's "suggestion box." According to historical records, during Yao's time, the "fei bao mu" were cross-beamed wooden structures.