About 3000 years ago, a mountain people from the Badakshan area of Central Asia (northeastern Afghanistan and southeastern Tajikistan), an important trading center through which the “Silk Road” passed, became tempted by wealth in lowlands to their west, which they’d become strong enough to consider appropriating. These people of Kamboja, or Kambujiya, had strong belief in hierarchy, divine will and the right of might. To them, to be able to take was a mandate to do so, within the natural, moral compass and order of things. In the 9th century BCE they took Persis (now Fars Province of Iran, where Shiraz is), then Anshan (in the Zagros mountains of southwestern Iran), a quite ancient civilization, and soon the whole Iranian plateau. The empire at around 500 BCE stretched from the Indus Valley in the east to Thrace and Macedonia; it eventually controlled Egypt and encompassed approximately 8 million square kilometers; in 480 BCE it is estimated to have had 50 million people. At its greatest extent, it had absorbed the modern territories of Iraq, Syria, Armenia, Jordan, Israel, Palestine, Lebanon, most of Turkey, parts of Libya, Georgia and Azerbaijan, much of the Black Sea coastal regions and extensive parts of Central Asia, Afghanistan, Saudi Arabia, Pakistan and Oman. These invaders may well have been the root of the Ksyatriya caste, India’s ruling military elite, who were in charge of protecting society by fighting in wartime and governing in peacetime. Gautama Buddha was most likely one of them (see the work of Ranajit Pal, who faces much disparagement but seems to me spot on). Some of these Persian Ksyatriyas created the Srivijaya maritime empire, a splinter group from which met other Kambojas who had come overland (eventually following the path of the Mekong) to the Tonle Sap in what was then the kingdom of Chenla (Zhenla) and is now Cambodia. These two groups, united by racial background and world-view, would have had trouble communicating verbally after over a millennia of differing influences on their language, but they saw the locals in quite the same way. Together they enslaved the aboriginals, built the extensive Angkor Wat complexes, became known as the Khom and eventually formed the core of Siamese royalty and what became Thailand. As less than 1% has great difficulty holding in slavery over 99%, when drought and the Black Plague hit about 1300 CE, the Angkor Empire crumbled, its edifices, by the time of the rise of Ayudhaya, left as a bad memory to get over-run by jungle, and the Khom were almost forgotten. Jit Phoumisak, called by some the only Thai intellectual, wrote about this, and seems as a result to have been executed. David K. Wyatt of Cornell University, the foremost historian on Thailand, might have wanted to write on it, too, but wanted even more to be able to return to Thailand for visits, so did not, although his later writings show interest in the surrounding controversies. Srivijaya, like the Dutch and British East India Companies, merely expropriated ports, with “Factory” warehouses, and didn't attempt administration of colonies (Ligor, now Nakorn Sri Thammarat a possible exception), but the Khom rulers of the Khmer (pronounced “kha-may", the first syllable just like the Thai word for slave) raised rule to an art form, beguiling a gullible public with magical incantations and other bewitchery for half a millennium.