 In the 3rd and 2nd centuries BC, the Parthians, a nomadic Iranian peoples, arrived in Western Asia.While they made large inroads into the modern-day territory of Afghanistan, about 100 years later another Indo-European group from the north—the Kushans (a subgroup of the tribe called the Yuezhi by the Chinese)—entered the region of Afghanistan and established an empire lasting almost four centuries, which would dominate most of the Afghanistan region.The Kushan Empire spread from the Kabul River valley to defeat other Central Asian tribes that had previously conquered parts of the northern central Iranian Plateau once ruled by the Parthians.