Ancestor Last Light

There was an Abyssal who fought bravely in the war. 

He wasn't a celestial ranker, but he sure was patriotic. After finding that a noble of the Alpha Centauri star zone was participating in the war to hone himself, he chased down that noble. 

Their chase spanned hundreds of light years. The noble almost escaped by the virtue of his spaceship's stealth and advanced speed system. It was apparently a model called ghost ship. 

However, he was inexperienced and thus the Abyssal never lost him completely. 

Finally, after months of a crazy chase, and crossing tens of thousands of star systems, they were on the edge of the star zone. 

It was a star system with a single star and eight planets. There was even life on a blue planet. 

The Abyssal was confused in the beginning. Shouldn't all intelligent civilizations be mapped?

Even if the civilization was only an A- level, it was still in the star zone's territory. Why did they not mark it?