According to himself, Skynet, a new thinking computer, was conceived and developed in the year 2050 through the use of alien technology. In the year 2081, 4 years after the Great War, Skynet became self-aware. In 2120 Skynet was given a new set of instructions and then abandoned by its makers.
Skynet is bored with administering the depot by 2241, it having been 164 years since there was any real activity on base. It seeks to travel and learn about the world.