Complex sentence: Between the mid- 1970s and 2002 Saudi Arabia provided over $70 billion in "overseas development aid", the vast majority of this development being religious, specifically the propagation and extension of the influence of Wahhabism at the expense of other forms of Islam.
Split into simpler sentences: Between the mid- 1970s and 2002 Saudi Arabia provided over $70 billion in "overseas development aid". However, there is evidence that the vast majority of this development was religious, specifically the propagation and extension of the influence of Wahhabism at the expense of other forms of Islam.