The People's Protection Units, also called People's Defense Units, is a mainly-Kurdish militia in Syria and the primary component of the Syrian Democratic Forces (SDF). The YPG mostly consists of ethnic Kurds, but also includes Arabs and foreign volunteers; it is closely allied to the Syriac Military Council, an Assyrian militia. The YPG was formed in 2011. It expanded rapidly in the Syrian Civil War and came to predominate over other armed Syrian Kurdish groups. A sister militia, the Women's Protection Units (YPJ), fights alongside them. The YPG is active in the Autonomous Administration of North and East Syria (Rojava), particularly in its Kurdish regions.