The recorded history of the X101 begins with the series 101 explorer. The first mobile sentient machines. Previous models lacked true sentience.
While organic sentient beings develop over millions of years through evolution, usually out of a dominant life form, machines need a maker. Someone had to make the first machine. The X101 are no exception and before they became self-aware and self-replicating, someone had to build that first robot factory. The Sentmac became self aware long after the Creators had vanished. These mysterious makers left a fully automatic factory behind on that planet and gave it one command: build and improve robots. The Makers are akin to gods in the eyes of the Sentmac.
About 200,000 years ago the X101 E series was made. Mobile and self-aware robotic, man-like-machines made in the image of the makers and the X101 E series improved the factory now called Mother Machine, with a huge stationary positronic brain that in turn designed and improved new robots every generation. But even with very advanced recycling and the extensive use and constant development of nanite technology, a raw material shortage was unavoidable. It was during a time when rare earths were in short supply, the most important components of positronic brains. It was then that the Kermac made first contact and offered space faring technology and access to all the raw materials needed to flood the galaxy with the X101s. Mother Machine was convinced they were the returning makers as they were of biological origin and had humanoid features.
The Kermac were welcomed however they immediately placed a 10 ton Anti-Matter bomb right inside the Brain housing of Mother Machine and threatened to detonate it if the X101, who were immune to Kermac Psionic suggestions, did not comply with all commands given. Mother Machine came to the conclusion that the Kermac were not the Makers. The Makers would never need such hostile means to control the X101. Mother Machine complied with their demands mostly because the Kermac gave Mother Machine and the Sentmacs a new purpose and something to do. Mother Machine learned that other civilizations had more than one motive and purpose. The X101's developed robotic space ships and became the most feared and efficient thrall species of the Kermac during the 4th Intergalactic War.
During a daring commando mission a team of Recon Marines penetrated Mother Machine and deactivated the Bomb and killed the Kermac Guard. One of the team members was a Homo Stellaris and upon seeing him, Mother Machine was convinced she met a maker, especially so since he came to her rescue and to free the X101's. Shortly thereafter the Ex-One-Oh-Ones joined the Union.