The Entharan colony was a Delta Quadrant settlement where Voyager bought weapons from the dealer Kovin in 2374, and where Seven of Nine accused him of assaulting her and stealing Borg nanoprobes.
The colony appears in the fourth-season episode Retrospect. Janeway negotiates there for an isokinetic cannon, and Seven of Nine works alongside the abrasive trader Kovin to install it, at one point striking him.
Under a form of hypnotic therapy improvised by the Doctor, Seven recovers what seem to be memories of Kovin stunning her and extracting nanoprobes in his laboratory. The Entharan magistrate opens an inquiry, and since reputation is everything in their commerce, Kovin flees.
The physical evidence turns out to have an innocent explanation, but he no longer trusts anyone. Firing on Voyager, he overloads his ship and is killed. The Doctor is left appalled at his own zeal.