Zanthia is a custom world and setting that uses the same core assumptions as Forgotten Realm 5e RAW:
Gods oversee the World
The gods are real and embody a variety of beliefs, with each god claiming dominion over an aspect of the world, such as war, forests, or the sea. Gods exert influence over the world by granting divine magic to their followers and sending signs and portents to guide them. The follower of a god serves as an agent of that god in the world. The agent seeks to further the ideals of that god and defeat its rivals. While some folk might refuse to honor the gods, none can deny their existence.
Much of the World Is Untamed
Wild regions abound. City-states, confederacies, and kingdoms of various sizes dot the landscape, but beyond their borders the wilds crowd in. People know the area they live in well. They've heard stories of other places from merchants and travelers, but few know what lies beyond the mountains or in the depths of the great forest unless they've been there themselves.
The World is Ancient
Empires rise and fall, leaving few places that have not been touched by imperial grandeur or decay. War, time, and natural forces eventually claim the mortal world, leaving it rich with places of adventure and mystery. Ancient civilizations and their knowledge survive in legends, magic items, and their ruins. Chaos and evil often follow an empire's collapse.
Conflict Shapes the World's History
Powerful individuals strive to make their mark on the world, and factions of like-minded individuals can alter the course of history. Factions include religions led by charismatic prophets, kingdoms ruled by lasting dynasties, and shadowy societies that seek to master long-lost magic. The influence of such factions waxes and wanes as they compete with each other for power. Some seek to preserve the world and usher in a golden age. Others strive toward evil ends, seeking to rule the world with an iron fist. Still others seek goals that range from the practical to the esoteric, such as the accumulation of material wealth or the resurrection of a dead god. Whatever their goals, these factions inevitably collide, creating conflict that can steer the world's fate.
The World Is Magical
Practitioners of magic are relatively few in number, but they leave evidence of their craft everywhere. The magic can be as innocuous and commonplace as a potion that heals wounds to something much more rare and impressive, such as a levitating tower or a stone golem guarding the gates of a city. Beyond the realms of civilization are caches of magic items guarded by magic traps, as well as magically constructed dungeons inhabited by monsters created by magic, cursed by magic, or endowed with magical abilities.