Long ago this planet was very different. There wasn’t the flat deep dirt we have today but large endless caverns and caves, more like an odd shaped honey comb of deep underground halls and dwellings that extend several miles long. Life thrived both above ground and below it. Then something came along to destroy all of that with one swipe. Leveling everything downward.
There was an advanced society of humans in this past that quickly died out as the planet turned to ice. The entire planet froze. But on the northern end of the region there were some caverns left where only a handful of humans waited out their existence. Unfortunately as time passed they went from a very advanced society mastering many sciences, arts and math to a simple uneducated one. It shifted to generations no longer interested in the technologies that had failed them, but only interested in survival. They were the only ones left on this frozen desolate planet. Their numbers begin to dwindle, their lives begin to become more barren, and just when you thought it was over for the human race, the ice age begin to melt. They would stay in their underground dwelling for a few more decades and then leave. It was decided they would split into different groups and repopulate different regions of the world. Humanity would begin again.
The Spirits pointed to a far north region of the planet, close to the north pole. Then Spirit explained that during this era what is now considered the north pole wasn’t north at all, but more on the side of the planet. This is where these cave dwellers existed. Spirits showed towering mountains with ice, and went underneath to show a strange looking vault. They kept a vault of many of their advancements over the centuries and its still there now.
All truth exists in the center of its two opposites.