Thailand and Ethiopia are often mentioned as countries which were not colonized. In the latter case the Mussolini tried but without much success. Thailand experienced different conditions. It is bordered by Malaysia and Myanmar, formerly Burma and both once part of the British Empire, by China, Laos, and Cambodia, the last two being part of French colonization as was Vietnam which is nearby. How did Thailand escape the European empire builders? Did it escape?
Two books on the history of Thailand, The King Never Smiles (2006) by Paul Handley, and William Stevenson, The Revolutionary King (1999) provide clues to how the country avoided imperial clutches. These included making territorial deals with neighbours and submitting to certain demands of foreign countries. (W. Stevenson, a Canadian author, was author of William Stephenson, A Man Called Intrepid}.
Neighbouring countries did make claims on Thai territory, but at times the government gave up territory on its borders, to the French and Burmese for example, rather than face submission to foreigners. Some of this land was subsequently reclaimed so that there has been a border-concertina process which warded off or responded to foreign pressures.
Fast forward to WW2 when Japan forced Thailand to provide a land route for the invasion of the Indian subcontinent. The death railway (Bridge on the River Kwai) is an example of what Japan had in mind to create a shortcut to India, one which avoided more dangerous sea lanes. One group of Thai politicians collaborated with Japan, assisted in building the railroad with the use of allied prisoners and Asians. There were far more Asians used to build the death railway than allied soldiers, and many more Asians who died in its construction. Another group of Thai politicians supported the allies but had to leave the country to do so.Towards the end of the war, the pro-Japanese faction turned on their occupiers and cooperated with the allied powers.
Although Thailand was not colonized, it avoided this by having to make deals with countries which might have colonized it. In the 1950s and 60s the country was supported by US policies and forces in south-east Asia. The US was concerned that Thailand would fall under the control of the Chinese communists as happened in Vietnam, Laos and Cambodia. Malaya, which included Singapore, also had a communist insurgency in the early postwar years but this was suppressed by British forces.
In sum, Thailand did not succumb to the traditional path of colonization, but in order to avoid it the country had to make concessions to foreign powers. While the political crisis now gripping Thailand does not have a direct colonial or foreign connection, some of the same Thai interests (urban versus rural) are still at play on the domestic scene. A good survey of the current situation is published in the Nov. 20, 2104 New York Review of Books, 51-53.