The Entity was designed to be a source of unlimited energy that would eliminate the need for limited-resource fuels. As a type of life collector, it would absorb the latent life energy expended in the natural flow of the universe and contain it within a single power source that the Kajeat could then use to power their whole society. However, when they turned the machine on, something went horribly wrong.
The device didn't just absorb the latent energy throughout the universe; it began to actively drain the life force from everything around it in an ever-increasing bubble. Slowly, everything in its entire dimension was consumed by the device's insatiable appetite. The collection of so many life forces into one single organism created a new type of life form, which became known as the Entity.
When the Travelers fled their home dimension, the Entity continued to reach out until it had consumed everything in its universe; it then lay dormant, unable to do anything else, slowly wasting away.
When Sado, one of the oldest Force-users of the Golden Age, reached through the Force to try and tap into a new source of power, he inadvertently made contact with the Entity. He was immediately consumed, though because he was not in the Entity's dimension, his life force was not drained completely; instead, he was filled with all the myriad life forces within the Entity, ceasing to be the one consciousness of Sado and instead taking on all the consciousnesses within the Entity itself. Sado gained virtually unlimited power through the Force due to the life energy at his disposal, and he became functionally immortal. At the same time, he gave the Entity what it had never had before: a true consciousness and capability of thought. At that, Sado realized that there was only one thing the Entity wanted; more life force.
Seeking out a way to allow the Entity into our dimension, Sado knew he needed to consolidate his power over the established universe. Reaching out to other Force-users of the time, he convinced many over to his cause, granting them a supply of life energy extending from himself that granted them the same powers and immortality that he had. This caused the first Great Schism among the Force-users, and those most powerful Force users who joined with Sado became known as the Shok'Thola, or Warlords.
However, when leaving, Sado discovered a young Force-user named Elan Mossin who had far more potential Force power than he did. At this discovery, the Entity transferred its consciousness and will into this young man, leaving Sado with a direct connection, but freedom in his own mind. This new leader, known as Altima, commanded the Altarin'Dakor for the next 25,000 years.