History of the Immortals

Dreamtime
Before The Gods can reclaim the earth they need warriors, so they send a pair of apes who are sympathetic to their cause on a mission around the world to gather up as many metals as they can. Upon gathering the metal, the fire goddess and the sun god forge The Immortals and the army is deployed to earth to fight the menace of the Evil Apes.

The Age of the Gods
With the Earth secure the Sun God orders the construction of the Sacred Temples around which grow The Sacred Cities, which are all part of The Sacred Kingdom. The Gods take turns governing the planet, each for a thousand years, teaching and guiding the people of earth who now include the Architects and the Builders. It is a time of peace. And then the War God shows up.

The Age of Kings
After the chaos of the Age of War, The Gods are nowhere to be found. The Immortals are left to govern themselves. They turn to a powerful military commander, known throughout the Sacred Kingdom for his strength and power when facing the forces of the War God. He is crowned king. This sparks thousands of years of rising and falling kingdoms. The population booms, though war and plague take their toll, and the immortals explore the rest of the mountains, still believing themselves too superior to settle in the valleys and lowlands.

The Age of The Warring Houses
Religious ideologies clash after millennia of rising tensions. The Kings have lost much of their power to the theocracy which is divided between The House, who accepted the existence of the War God and welcomed him into the pantheon, and The Conclave, who hate and fear the war god and will fight to keep him out of the pantheon at all costs. The Kingdom is ravaged and the conflict spills into the northern river valley, which has been having its own civil strife as well. The Northern River Lords are united under one banner and that banner is carried to the heart of the Sacred Kingdom. The struggles between House and the Conclave are made obsolete, though they still fight in the shadows.

The Age of Dynasty
After consolidating two kingdoms of warring kingdoms, The Dragon Lords of the North usher in the longest period of peace (mostly) and prosperity (depending who you are) of the entire span of Immortal History. Having pushed all the way to the edges of the map, they build the first ships and begin sea exploration, discovering new lands and setting up mostly small trading posts. However, their air of superiority and lust for fertile southern farmland proves to poke quite the bear.

The Age of The Conquerors
After thousands of years of smaller conflicts with the immortals the nomadic tribes of the southern centaurs are united behind one really big and scary centaur who conquers The Sacred Kingdom and takes the throne for himself. It's a big embarrassment for The Immortals. They don't let the centaurs get entirely comfortable.

The Age of the Phoenix
Out of the ashes of the Conquered Kingdom, The Immortals rise once again. They explore the world and trade with its people (humans and dwarves). They build temples on far off islands. One of those temples is destroyed by a storm while the head monk is away fighting a war of succession for the Imperial Immortal Throne.