According to some scholars, including philologist J.W. McCrindle, the name "Yūsəpzay" or "Īsəpzay" is derived from the tribal names of "Aspasioi" and "Assakenoi" – the ancient inhabitants of the Kunar Valley and the Swat Valley who offered resistance when Alexander invaded their land in 327–326 BCE. According to historian R.C. Majumdar, the "Assakenoi" were either allied to or a branch of the larger "Aspasioi", and both of these ancient tribal names were probably derived from the word "Aśvaka", which literally means "horsemen", "horse breeders", or "cavalrymen" (from "aśva" or "aspa", the Sanskrit and Avestan words for "horse").