The ancient Greco-Roman geographer Strabo noted that the four tribes that took down the Bactrians in the Greek and Roman account – the "Asioi", "Pasianoi", "Tokharoi" and "Sakaraulai" – came from land north of the Syr Darya where the Ili and Chu valleys are located. Identification of these four tribes varies, but "Sakaraulai" may indicate an ancient Saka tribe, the "Tokharoi" is possibly the Yuezhi, and while the Asioi had been proposed to be groups such as the Wusun or Alans.