 Darius spent the winter of 516–515 BCE in Gandhara, preparing to conquer the Indus Valley.Darius conquered the lands surrounding the Indus River in 515 BCE.Darius I controlled the Indus Valley from Gandhara to modern Karachi and appointed the Greek Scylax of Caryanda to explore the Indian Ocean from the mouth of the Indus to Suez.