Syrian civil war
The second proxy war is between Iran and Saudi Arabia. Iran has supported the Syrian government since the start of the conflict. The reasons for this are that Iran and Syria have long been allies, and the survival of the Syrian regime is essential for Iran's geopolitical interests.  Iran has supported the Syrian regime by providing military supplies, helping pro-Assad militias and sending Hezbollah troops. Saudi Arabia, on the other hand, has since 2012 been funding and arming the rebels, together with Qatar.  The main reason for this is to counter Iranian power and achieve regional dominance.