The thing that costs the most conflict in the Middle East really depends on what people group:
For large, powerful countries like the US & Russia, for example, conflict arises from them trying to secure as much oil for themselves (oil is referred to as black money by some people) as almost every technological product uses oil one way or another (even things like your phone case that is made of plastic, because plastic is made from oil).
For fanatic groups, like the Taliban, and the current-group-in-power the ISIS, they start conflict because they want want people in the area to follow a specific religion, and is not afraid to take extreme measures to make people believe in their god.
hope this helps
