Remnants of Bo village. Bo people lived in this district under the Xia, Shang and Zhou dynasties. Their civilization flourished already in 1100-256 BC. The Bo populated Yibin were called Dao in Chinese, thus the county encompassing Yibin was called Bo Dao county. The Bo buried their dead in hanging coffins high on rocks. The most complete description of this mysterious custom in English (that I've managed to find) is right here: http://www.china.org.cn/english/culture/55407.htm