In technological innovation, the early toe loop stirrup is credited to the cultures of India, and may have been in use as early as 500 BC. Not long after, the cultures of Mesopotamia and Ancient Greece clashed with those of central Asia and India. Herodotus (484–425 BC) wrote that Gandarian mercenaries of the Achaemenid Empire were recruited into the army of emperor Xerxes I of Persia (486–465 BC), which he led against the Greeks. A century later, the "Men of the Mountain Land," from north of Kabul River, served in the army of Darius III of Persia when he fought against Alexander the Great at Arbela in 331 BC. In battle against Alexander at Massaga in 326 BC, the Assakenoi forces included 20,000 cavalry. The Mudra-Rakshasa recounted how cavalry of the Shakas, Yavanas, Kambojas, Kiratas, Parasikas, and Bahlikas helped Chandragupta Maurya (c. 320–298 BC) defeat the ruler of Magadha and take the throne, thus laying the foundations of Mauryan Dynasty in Northern India.