Kautilya (c. 4th century BCE) in his Arthashastra mentions the protection of the kingdom's shipping and destruction of those threatening it. Although navy is not elaborately mentioned as one of the principle arms of Indian military in the Arthashastra, Megasthenes mentions it. Megasthenes mentions military command consisting of six boards of five members each, (i) Navy (ii) military transport (iii) Infantry (iv) Cavalry (v) Chariot divisions and (vi) Elephants. During Mauryan empire, Indians had already made trading connections in South east Asia from Thailand and Malaysia peninsula to Cambodia and southern Vietnam. Mauryan period seals and inscriptions has been discovered at the ancient port cities of Thailand and Southern Vietnam. Sea lanes between India and neighbouring lands were the usual form of trade for many centuries, and are responsible for the widespread influence of Indian culture on other societies, particularly in the Indian Ocean region. Powerful navies included those of the Maurya, Satavahana, Chola, Vijayanagara, Kalinga, Maratha and Mughal empires. The Cholas excelled in foreign trade and maritime activity, extending their influence overseas to Southeast Asia and China. Early literary evidences The Indian shipping and maritime trade activity have been referenced in Arthashastra. Kautilya mentions the superintendent of ships as an officer which was supposed to look after the ports and shipping and security of maritime traders. Four categories of ships have been named, Commercial (Potavanika), Private (Svanaya), Royal (Rajanau) and warship (Himsrika). Commercial ships are further divided into Merchant ships (Samyati) and passenger ship (Pravahana). A Jain text 'Angavijja' and Periplus of the Erythraean Sea. both dated to early centuries AD mention Indian ships called Trappaga (Tappaga) and Kotyamba (Kotumba) which were classified as mid sized vessels, larger than Kattha and Velu but smaller than Pota with greater space and suitable for high sea yovages, Chandraketugarh seals provide names for Indian vessels as "Indra of the ocean" (Jaladhisukra), scholars have noted a new steering mechanism employed by this ship whose name suggests it as a deep seafaring ship and "journey of three directions" (Tridesayatra). Angavijja mentions thirteen categories of ships. Gupta Empire Navy The five arms of the Gupta military included infantry, cavalry, chariot, elephants and ships. Gunaighar copper plate inscription of Vainya Gupta mentions ships but not chariots. Ships had become integral part of Indian military in the 6th century AD. Chola expeditions The Imperial Cholas initiated their grand naval conquests during the reign of two of its