By the 1850s, when the monarchy was confronted with the challenge of conceding trading rights to western powers. ubstantial economic chang had already taken place towards a exchange economy,and the role Bangkoh and its hinterland had been central.Under increasing pressur from British trading interests, and acutely aware of the expansion western colonial power in the immediate region, King Mongkut(Ran IV) signed a commercial treaty with Britain in 1855(the Bowring Treat which was closely followed by similar agreements with other weste powers. The treaties reduced import-export duties, abolished customa shipping fees and removed many trading monopolies still in place export products in the form of the private tax farms.