Most Wahhabis are on the Arabian Peninsula (Qatar, United Arab Emirates, and Saudi Arabia.) Half of the Emiratis and Qataris are Wahhabists, and maybe a fifth of all Saudis are, too.
Wahabi’s in the late 1800’s almost destroyed the Ottoman empire because they believed that other muslims were committing shirk. The House of Saud would not exist today if the House of Saud did not come to a formal arrangement with this group back then. Wahabists marched from Turkey to what is now Isreal all in the name of pushing the Jews into the sea. There is a book by Dori Gold should you be interested in reading about the Wahabists, the most violent sect in Islam. Today, most deny the existance of the Wahabi’s but they exist under the protection of the House of Saud in Saudi Arabia.
I would not be surprised if the ISIS faction is based on the wahhabis faction.