The Persian kings Darius and Xerxes of the Achaemenid Empire had no claim beyond the present-day Khyber Pass and had no knowledge of the Punjab region according to Strabo. Similarly, the people of the tributary rivers of the Indus, modern-day Punjab, also had never heard of the past Persian kings along with the people of the Indus, who according to Megasthenes were not even aware of the vast Achaemenid Empire.