Magna and The Walking Mountain City

No one goes beyond the Vale, for the mountains are dangerous and it's said a great monster resides there. Some believe that it protects the denizens of The Ander Vale, but others think it's purpose is to keep them inside and away from the outside world. Whatever the case may be, those who decide to venture into the mountains never return, or come back so scared they're unable to speak of what they saw.

Summary

A Great Monster known as Magna walks among the mountains, protecting the people from the horros beyond The Ander Vale. It's said to be as tall as a mountain, and so powerful that not even the strongest could defeat it. A civilization is said to be on it's back, comprised of those lost or abandoned in the mountains, given mercy by Magna.
Every month a different part of The Ander Vale holds a celebration for Magna, leaving food at drop points in the mountain side for it. Magna has become a central religion to The Ander Vale.

Historical Basis

The Ander Vale is one of the many scattered bastions of life and civilization in the world, and in order to defend it from becoming a wasteland like most of the world, an Awakened Tarrasque (See Awaken spell) acts as a Guardian to this place. The Ander Vale is also the final resting place of something called The Keeper. (Only Magna knows this information)
The civilzation on its back is not quite a civilzation. A tribe of tieflings called The Wastelanders once lived on the outskirts of The Ander Vale in order to help travel between areas of civilzation. Upon gaining the trust of Magna, the two came to an agreement. The Wastlanders would continue their nomadic lifestyle as guides across the wasteland, and Magna would be their home, the place where these nomads would meet or take outsiders if they needed shelter.

Spread

Magna has become a central point to the official religion of The Ander Vale, but many don't know what type of creature it is. Some refer to is as an earth elemental, others as a dragon, and some even think it's the tallest mountain in the mountain range. And of course, there are many who believe Magna doesn't exist at all.

In Literature

Many authors have written fiction revovling around the birth of Magna, and its ideals as to why it protects or acts as keeper to those in the Ander Vale. Bold authors include it as a dystopian king like ruler who thinks the people of the Ander Vale are small and meaningless.

In Art

Magna has been drawn in many forms, none of them the Tarrasque. Though it is very present in this world, it is rarely seen.