Yarosh has denied any connection with Chechnyan rebels, even though given the heat of the moment in Ukraine, he could be expected to boast of any exploits in fighting Russians if he had them.
Right Sector most certainly DID fight against the Russians in Chechnya:
“During the first Chechnya war in 1994, Muzychko commanded a UPSD Viking squad and fought the Russians alongside Chechen field commander Shamil Basayev, the leader of the radical wing of the insurgency.
In Ukraine it has been reported that the president of the rebel Chechen republic, Dzhokhar Dudayev, decorated Muzychko with the order Hero of the Nation and named a street after him.
Moscow authorities claimed that Muzychko killed at least 20 Russian soldiers in the Chechen war and brought a criminal case against him for that.”