The Ten Thousand Beast Heavens was a place with an extremely complicated terrain, set in the mountainous regions of the north with various tall rolling mountains. Most important was the two lines of mountains that crossed the north of the WanShou Empire, of which there was one intersection of the two which was actually crossed with another mountain line, forming a triangular basin.
Compared to the rest of the icy snow of the north, this particular triangular basin was at a much higher temperature than the rest of the surroundings; in fact, many vegetation that only grew in temperate climates could be found there. This unique basin was actually rather huge, and with such a suitable climate for living in, and over hundreds and thousands of years, more and more powerful Heavenly Beasts were either attracted here or grew strong here. As such, this triangular basin was known as the Ten Thousand Beast Heavens.