The Varni are a reptilian race that evolved very slowly to sentience. The old Varni Republic was crushed by the more aggressive, and stronger, Kilrathi Empire. Those few Varni that survived were kept as slaves, or were fated to never see their homes again. The short campaign against the Varni was lead by Joor'rad nar Kiranka, who would later become the final Kilrathi Emperor. The only setback for the Kilrathi in the campaign occurred when the Varni were able to organize themselves and concentrate their fighters on a single Kilrathi Cruiser. This unprecedented attack nearly managed to destroy the capital ship, before the Varni Wing Commander was killed. When this occurred, the Varni fighters became disorganized, and were easily destroyed.
Source: WC CIC Encyclopedia