The Yuuzhan Vong had begun scouting the galaxy in preparation for their invasion at least as early as 32 BBY when they began their attack upon Zonama Sekot, and possibly as far back as the Old Sith Wars. In 27 BBY, a small scout force encountered a Chiss fleet under Admiral Ar'alani, and attacked with immediate ferocity. Despite being outnumbered by the Chiss, the Yuuzhan Vong fleet was only destroyed with great difficulty and casualties. There were no survivors for the Chiss to recover, although they did learn some of the Yuuzhan Vong biotechnology.
When Special Task Force One arrived in the Unknown Regions and Kinman Doriana used the threat of Jedi falling into the hands of the Yuuzhan Vong as a pretext to destroy the Outbound Flight, Thrawn was convinced to agree to the plan due to the knowledge of the difficulty the Chiss had faced against the limited Yuuzhan Vong scout force.
- Outbound Flight (First mentioned)
- Choices of One (Indirect mention only)
- Invasion 0, Part 1 (Mentioned only)