First contact with this race was made during a scouting mission for Galacite on the fourth planet of an uninhabited star system. The only evidence of a civilization is a colony that appears to have been long abandoned. While exploring a network of caves trying to find the source of the Galacite, several chameleon-like humanoids appear out of nowhere, their crusted-earthy appearance blending perfectly with the surrounding rock.
The Sikari ask very specific questions trying to determine if and how they were detected. Commander Chakotay offers to help the Sikari pinpoint the things that caught Voyager's interest, and conceal them more completely. It was the ruins and the Galacite readings that brought them here, and those can be hidden better and Voyager would gladly assist in this effort and then leave the Sikari alone for good.
The Sikari were attacked 60 years before, and in less than an hour their entire civilization was lost. There were a fortunate few who escaped into the mines, and they've hidden here in safety ever since. The Sikari agree to an information exchange as well as providing Voyager with Galacite.
Returning to the surface, Commader Chakotay discovers the reason for the Sikari's wish to remain undetected, when he discovers the remains of a Borg drone