Led by Kurds, the YPG evolved over time into the Syrian Democratic Forces (SDF): a multi-ethnic, multi-religious force in which all the indigenous peoples of the region are represented. Arabs, Assyrians, Armenians, Yezidis, Circassians and Turkmen have fought alongside Kurds to defend their homeland. By 2019, when the SDF had liberated all of Syrian territory from ISIS control, there were some 100,000 fighters (including SDF and Internal Security Forces) under the leadership of SDF commander-in-chief Mazlum Abdi, a Syrian Kurd and former Kurdistan Workers’ Party (PKK) cadre.[2] The majority of his rank-and-file fighters, however, were Arabs.