In 2243 AD, just as humans were preparing to migrate on a large scale to Fenyoman-16Z, a habitable planet 3.2 Billion light-years away, the Zerg invaded the Earth. Although humans won the victory, they also suffered heavy losses.
This war is called the "HZW War" - Human Zerg War.
In 2298 AD, the plan for humans to colonize the habitable planet Fenyoman-16Z was once again put on the table.
One-third of the population left the earth on the second faster-than-light manned spacecraft and headed for the habitable planet Fenyoman-16Z, which is 3.2 Billion light-years away.