If someone had explored the entire mysterious realm, they would have discovered that this subterranean secret realm was vast, spanning about 700 kilometers. The total length of various caves and chambers exceeded 300 kilometers.
The caverns were largely divided into four areas: the sparse cavern group in the high terrain of the northwest, the karst caves in the lower terrain of the southwest, the upper reaches of the Dark River in the northeast, and the lower reaches of the Dark River in the southeast. The four areas were connected by a massive underground river, surrounded by many tributaries and dried-up old riverbeds (now passable cave channels). Some formed loops, while others led to dead ends; ordinary people could easily become disoriented within.
