Sykar was a planet in the Uncharted Territories inhabited by Sykarans, a Sebacean people Aeryn Sun described with derision as a primitive, labouring, distant cousin species, and visited by Moya and her crew.
The planet Sykar was described as having been a beautiful garden world but at some point in the past the Peacekeepers secretly took control of the planet, installing a puppet government, and converting the planet's entire civilization into one big Tannot root production facility. The root was collected by the peacekeepers, and underwent a process which converted it to Chakan oil, a Peacekeeper weapon fuel. The consumption of the root made the indigenous population docile and blissful, happy to work the fields every day, believing all they were told and accepting any command given.
A resistance existed and ultimately the plot became exposed, with the help of Crichton, and Rygel's digestive system somehow resembling the Chakan oil manufacturing process. In the end, the puppet government and resistance joined forces in the hopes of repelling future Peacekeeper incursions. ("Thank God It's Friday... Again")