Complex sentence: Another major theme is the Hexamon's ongoing war with an advanced and implacably aggressive alien race known as the Jarts, who have entered and taken control of large sections of the Way, beyond 2x10 ^ 9 kilometers (2 billion kilometers).
Split into simpler sentences: Another major theme is the Hexamon's ongoing war with an alien race known as the Jarts. The Jarts come from further down the Way, beyond 2x10 ^ 9 kilometers (2 billion kilometers).