The end of the 9th century, the Cholas had the advantage of being in control of both the East and West coast. The Tang dynasty of China was their major trading partner, along with the Srivijayas of Malaya and the Abbasid Caliphate of Baghdad. China was their major trading partner, and you had trade guilds, which needed the approval from the king and a licence from customs department to embark on such a campaign. While spices, cotton, gems were shipped to China, in turn they got incense, iron and silk from there. During the period of the Song Dynasty, an envoy of the Cholas visited their court in 1077 AD, most likely during Kulothunga Chola’s time, as per records. The Cholas got copper coins, in exchange for spices, glass articles. It was a mutually beneficial cooperation with Cholas adopting techniques like independent water tight compartments, the mariner’s compass and flamethrowers for naval warfare.