THE basis of Thailand's political security has been altered from time to time to meet the changing stresses and strains created by great powers in the Far East. In the process of political evolution the Thai people and their politicians have shown a great deal of flexibility. Until the middle of the nineteenth century Thailand regarded China as the principal political force in the Far East and accordingly arranged her policies and practices to dovetail with China's. There was no great power comparable to China in the Far East which could have been used to offset or balance the power of China. China was in fact as well as in name the "Middle Kingdom." From the middle of the nineteenth century until as late as 1932 the politically great in southeastern Asia were not oriental but occidental powersGreat Britain and France. By the end of the nineteenth century it became apparent that Britain was the primary and France the secondary power. Thailand's politicians consequently rested the security of the nation on their ability to balance the ambitions of these two great powers. It was not until 1932 that Thailand began to suspect that Japan was replacing France as the second most important power in southeastern Asia. And it was not until December, 1941 that it became evident that Japan was challenging Great Britain's position. Since 1941 Thailand has been forced to shift her basis of security from that of balancing two great powers to that of getting along with one great power-Japan. The history of Thailand's foreign policy illustrates Thai adaptability and gives some idea as to what may be expected from Thailand in the future. In the period preceding the nineteenth century, China regarded Thailand as a tributary nation and demanded annual tribute which the Thai paid irregularly. The practice of sending Thai envoys to China had been customary during the Sukhothai period (1257-1350), the Ayutthia period (13 50-1767), the Thonburi period (1767-1782), and during the reign of Rama I (17821809) .1