1000 years before the human arrival the ancients where a primitive race with low intelligent but high strength and agility. They were far taller than humans, and were the best hunters of their time.
100 years later they conquered a large portion of the world only stopping at the spirit lands.
In the same year the species found a relic a old machine, considering it a sign of triumph over the spirits.
100 year pass again whit bloody battles whit the spirits but the could not defeat them. At the same time the women and the weaker of the men found a way to utilize the machine to increase their development speed to match even the strongest of their species.
200 years later the war ended with the spirits dominating due to a technological revolution. A civil war break out between the technology users and the primitive and older warriors. The technological part was greatly out numbered but understood how wrong it was to attack the weak. The spirits aided this side. This was the first cross-species alliance in history.
10 years later the alliance defeated the primitive tribes.
The next 190-200 years flew past the alliance with minor conflicts but the alliance held and worked to un-do the damage of the long war.
At the last 400 year the Ancients greatly changed. they kept their height, but lacked muscles as their technology developed: relying less on raw power and more on using their intellect.
In recent years, they have successfully established a base on the moon to test experiments in low gravity, in hopes of reaching further into space as their technology continues to improve.