You don't say where you are, but I know a group that would be perfect for what you want. They are based in Scotland but are currently touring in the US. They are almost exclusively percussion based, they are called "Clann an Drumma" which means "Children of the Drum". They generate an unbelievable energy when they perform. Check out their website at click here . You can pm me if you're interested because I'll be seeing them in a couple of weeks. I also have a friend who has written some excellent songs with Arthurian based subject matter.