The Eight Towers Mountain was surrounded by seven mountains. Because the terrain was uneven, every rainy season, there would always be several flying waterfalls on the Eight Towers Mountain. The water passed through the small river in the valley and flowed into the valley at the back of the mountain, forming a lake.
There was an underground river under that lake that led to the outside world of the Yin Clan. Back then, Zhou Buwen had sneaked into the Yin Clan through that underground river.
However, very few people knew about the existence of the underground river. Only the Patriarch and elders knew.
The reason why Yu Huang knew was also because of Yu Donghai.
Yu Donghai was Yin Mingjue's most trusted right-hand man. Yin Mingjue had once told Yu Donghai about the existence of the underground river. Unless the Yin Clan was in danger, the existence of the underground river wouldn't be made public.
