Wahhabism to ISIS: how Saudi Arabia exported the main source of global terrorism

Although IS is certainly an Islamic movement, it is neither typical nor mired in the distant past, because its roots are in Wahhabism, a form of Islam practised in Saudi Arabia that developed only in the 18th century.
http://www.newstatesman.com/world-affairs/2014/11/wahhabism-isis-how-saudi-arabia-exported-main-source-global-terrorism