Along the route from the mouth of the Chao Phraya River until Ayutthaya, there were guard vessels and strict vigilance. The ship captains needed to disembark and register their names and all their goods and armament at a checkpoint called ‘Ban Chao Phraya’ manned by a Mandarin at the mouth of the river. (5) After the registration, a passport was obtained to proceed to Ayutthaya. Denton, one of the English factors in Ayutthaya, recorded that "when going first to the capital, they learned that the crews of two Japanese junks, then in the river, had traded by force, having entered the city walls without a license. The result was that eight of their number were killed in one day, whereas if they had first procured the necessary Tarra or license, all would have been well." [8]
Cornelis van Nieuwenroode (?-1633 CE), working for the Dutch East India Company, mentioned for the first time the presence of a Customs House in Bangkok in his 'Vertoog van de gelegenheid des Koningrijks van Siam' published in 1622 CE. He explains the toll procedure for ships going up the Chao Phraya River to Ayutthaya.
“Approximately 5 miles along the same river lies a small walled town at a river junction, called Banckock, where the King's first tollhouse is located, named Cannon Banckock. Here, all junks or ships (regardless of their nation or place of origin) must anchor and declare their intentions, their place of origin, the number of people, armaments, and the merchandise they carry, in order to be charged a toll. After settling the toll, they receive a toll or license document, which allows them to proceed upstream to about a mile from the city of Judea, where the second toll or license house is located upon entry (and upon departure, it is the first), named Cannon Batenauw. Here they must anchor again and be charged a toll without any payment, serving only as additional security so that neither the lord nor the foreigner is defrauded or falls short. After showing their toll document, they may continue to or within the city walls and conduct their business as they wish without being hindered by anyone. It is understood that upon departure, they must pay the same toll as upon entry and obtain a license to leave. Upon paying the toll at Cannon Banckock (which upon departure is the second and final tollhouse), just as when entering at Cannon Batenauw, they must present it without paying anything further. All prahus, regardless of how small they may be, where they come from, or where they intend to go, whether loaded or not, are subject to proper inspection and must comply, under penalty of the prahu and the loaded goods being forfeited if they pass or bypass the aforementioned Cannons or tollhouses without a license or without stopping to be addressed, etc.” [9]