evidence: Arab-majority Deir Ezzor province, a resource-rich region which borders Iraq, is bisected by the Euphrates river and is home to dozens of local tribal communities, some of whose fighters joined the SDF in its battle against IS. [...] Control of Deir Ezzor is split between the US-backed SDF to the east of the Euphrates, and Iran-backed Syrian government forces and their proxies, including fighters from Iraq, Afghanistan and Pakistan, to the west.