INTRODUCTION The predecessor of the Kushān dynasty was the Xihou 翖侯 of Guishuang 貴霜, one of the five Xihou 翖侯 in the state of Daxia 大夏. The Xihou 翖侯 of Guishuang 貴霜 came originally from the Gasiani, one of the four Sakā tribes that invaded the Greco-Bactrian Kingdom. In around 140 BCE, various tribes of the Sakās crossed the Syr Darya and moved south. One group of them entered Bactria, and destroyed the Hellenic kingdom there. The state they founded (which seemed to comprise mainly the Tochari) was denoted as Daxia 大夏 in the “Dayuan liezhuan 大宛列傳” of Shiji 史記 (ch. 123). “Daxia 大夏” [dat-hea] appears to have been a transcription of “Tochari”. In 130 BCE, the Wusun 烏孫 launched an expedition against the Da Yuezhi 大月氏 with support from the Xiongnu 匈奴; they defeated the latter and occupied the valleys of the Rivers Ili and Chu. The defeated Da Yuezhi 大月氏 migrated west and reached the valley of the Amu Darya, defeating in turn Daxia 大夏 and occupying its territory. The Da Yuezhi 大月氏 ruled Bactria and its surrounding area directly, and controlled the eastern mountain region by means of the so-called five Xihou 翖侯. The five Xihou 翖侯 were all the Daxia 大夏 people, who were propped up and used as puppets by the Da Yuezhi 大月氏. The Xihou 翖侯 of Guishuang 貴霜 who later overthrew the Da Yuezhi 大月氏 forces must have been a descendant of one of them. The exact date of the emergence of the five Xihou 翖侯, including the Xihou 翖侯 of Guishuang 貴霜, cannot be known today. There was no major overlord or chief in the state of Daxia 大夏, but a great number of “minor chiefs” had previously ruled independently there. It is possible that the five Xihou 翖侯 were originally “major overlords” of the former state of Daxia 大夏, who were received by the conquerors and continued to exist after the Da Yuezhi 大月氏 had conquered Daxia 大夏. If this is correct, the date when the Xihou 翖侯 of Guishuang 貴霜 and other Xihou 翖侯 appeared could not have been earlier than 140 BCE, when the Sakā tribes including the Gasiani moved south from the northern bank of the Syr Darya and destroyed the Greco-Bactrian Kingdom. It is also possible that, after they had conquered Daxia 大夏, the Da Yuezhi 大月氏 appointed five Daxia 大夏 natives who had close relationships with the Da Yuezhi 大月氏 to serve them as Xihou 翖侯 in controlling a part of the former Daxia 大夏. If this is true, the date when the five Xihou 翖侯 who were “subject to the Da Yuezhi 大月氏” appeared could not have been earlier than 129 BCE, when the Da Yuezhi 大月氏 conquered Daxia 大夏. Qiujiuque 丘就卻 (Kujula Kadphises), the founder of the Guishuang 貴霜 dynasty, had been the Xihou 翖侯 of Guishuang 貴霜 in the state of Daxia 大夏. He had allied or united by marriage with Hermaeus (Yinmifu 陰末赴), the Hellenic king in western India, and thus overcome the other four Xihou 翖侯. He established himself as king; his state was named Guishuang 貴霜 after the four other Xihou 翖侯 had been destroyed. After c. 50 CE, he seized Paropamisadae from Gondophares or his successor who came from Sakāstan (the upper and middle reaches of the present-day Kabul River).