It is unknown how the ten tails came into existence. However, it is known that the ten tails caused a lot of destruction. Centuries before the beginning of Naruto, the Sage of Six Paths stopped the beast by sealing it within his body, becoming the first jinchuriki. He knew, however, that once he died the seal would break and the ten tails would cause more damage. So,the Sage of Six Paths split the chakra of the ten tails into nine seperate entities, the tailed beasts now known in the Naruto world. The Sage of Six Paths then encased the remains of the ten tails into a stone prison and sent it into space, creating the moon.
The ten tails is vaguely humanoid with an eye that looks like a fusion of the Sharingan and the Rinnengan.
The ten tails is a fusion of the nine tailed beasts, making it stronger than all of them. It should be noted that the Sage of Six Paths made nine tailed beasts instead of keeping one, making it very powerful.Only A Eternal Mangekyo Sharingan can Control The Beast.