Tractites were natives of Tractis.
The Earth Empire invaded Tractis, enslaving and killing the Tractites. A few escaped and discovered a Time Tree, which they used to travel to Earth's prehistoric past and prevent humans from evolving, creating an alternate timeline where Earth was known as Paratractis. One Tractite ended up in the 20th century, where he allied with Jacob Hynes.
In one universe, Tractites were one of the species who had the potential to destroy Gallifrey. (PROSE: The Infinity Doctors) Marnal pondered if they were the species who destroyed Gallifrey. (PROSE: The Gallifrey Chronicles)