The Federation's first contact with the Kazon was by the U.S.S. Voyager when it was sent to the Delta Quadrant. The Kazon were once under control of a race called the Trabe, until they overthrew the Trabe and divided into different sects.
Some sects are: Ogla, Nistrim, and there are many more.
Their ships consist of huge battleships, bigger than the Dominion Battlecruiser and Romulan D'Deridex Warbird, to small shuttles.