XENOMORPH TIMELINE
When a human spaceship discovers a vast egg-shaped vessel in Saturn's orbit, they zero in to investigate the anomaly. They force their way aboard, finding evidence of an ancient alien civilization of peaceful creatures, now eradicated by an unknown foe. Three teams split up to explore the ship. But already the Aliens have awoken. The first of all the battles unfolds...
Before Ripley, there was a first encounter. Someone on Earth knew about the Aliens. Someone battled them, and survived. Aliens and humans have fought before.
Aliens: Steel Egg is a book released in 2007 that takes place in 2090 in the Alien timeline. In the Legacy Alien timeline, it comes before Aliens: Earth Hive (2092).