The shamans can be part of Orlanthi clans, but they usually form their own independant group. To earn a living, they often send spirits to curse other clans in order to receive payement to remove the curse. These curses are often benign, although if you treat the shamans poorly, they may side with your enemies and send greater curses on their behalf.
In a Tribe
There is a clan known for a large boulder with war powers that reveres shamans more than godi. If you want them in your tribe, you might have to agree to respect shamans more than usual. If this clan is in your tribe, you will have an easier time finding shamans during events, provided you keep paying them the required respect.