Saudi Arabia is set to host a series of talks Tuesday with the Syrian rebels fighting President Bashar Assad's forces, Reuters reported. The goal of the meeting is to form a united antigovernment coalition in order to negotiate with the Assad regime.

"Saudi is a pivotal state in the region and for it to take this step -- to host a conference of the Syrian opposition factions -- certainly something real will result from it," the leader of one of the rebel groups, who preferred to remain anonymous, told Reuters. At least 65 representatives are expected to attend the meeting in Saudi Arabia.

Syrian rebel groups have been fighting Assad's forces since 2011 when antigovernment protests evolved into an all-out civil war. As the conflict has raged in the past four years, leaving more than 220,000 dead and displacing several million, the antigovernment factions have become increasingly sectarian and fractious.

The extremist organization known as the Islamic State group, ISIS, or Daesh emerged as militants attempting to depose Assad while taking over vast swaths of Iraq and Syria. Many of the other rebel groups are now fighting both Assad's forces and ISIS.

There are as many as 1,000 rebel groups in Syria, totaling 100,000 soldiers, BBC reported. The Free Syrian Army and its allies are one of the largest and most powerful rebel coalitions, started by a former Assad colonel and other military deserters. The U.S. has funded certain groups that are part of the Free Syrian Army coalition.

The Kurdish military, made up of fighters from the ethnic minority group in Turkey, Iraq and Syria, have been one of the top groups fighting ISIS on the ground. They were not invited to the talks in Saudi Arabia, however.

Iran has allied with the Assad regime in the conflict, sending forces to support the government, and the Saudi conference has angered the Iranian government, Al Jazeera reported Tuesday.