PHO Khun Ramkhamhaeng, has the trade with abroad, Argosy, and in the reign of Somdet Phra Narai khotkra were neck in order to connect with the Andaman Sea, Gulf of Thailand to the carriage of goods by sea.
In the reign of King Ramkhamhaeng a trade with foreign junk. And in the reign of King Narai the Kra Canal to connect the Gulf of Thailand and Andaman Sea to facilitate the transport of goods by sea.
In the reign of King ram khamhaeng had trade with foreign man. And in the reign of King Narai to dig the KRA isthmus to connect with the Andaman Sea to the Gulf, convenient transport of goods by sea