According to the Encyclopædia Britannica, "A quarter to a third of the population of some areas of Thailand and Burma were slaves in the 17th through the 19th centuries." This has been ascribed to the long succession of able rulers in the past four centuries who exploited the rivalry and tension between the French and British Empire.In 1896, Britain and France guaranteed of the Chao Phraya valley as their buffer state (not the whole of Siam), while the remaining parts of Southeast Asia were colonized by the western powers.
Thailand retained a tradition of trade with its neighbouring states, from China to India, Persia, and Arab lands.
Ayutthaya became one of the most vibrant trading centres in Asia.
By outsiders prior to 1949, it was usually known by the exonym Siam (Thai: with the Sanskrit Śyāma (श्याम, meaning "dark" or "brown").
The names Shan and A-hom seem to be variants of the same word.
Similar to other regions in Southeast Asia, Thailand was heavily influenced by the culture and religions of India, starting with the Kingdom of Funan around the 1st century CE to the Khmer Empire.
Indian influence on Thai culture was partly the result of direct contact with Indian settlers, but mainly it was brought about indirectly via the indianized kingdoms of Dvaravati, Srivijaya, and Cambodia.
After the fall of Ayutthaya in 1767 to the Burmese, Taksin moved the capital to Thonburi for approximately 15 years.
The current Rattanakosin era of Thai history began in 1782 following the establishment of Bangkok as capital of the Chakri dynasty under King Rama I the Great.
Following the decline and fall of the Khmer empire in the 13th–15th century, the Buddhist Tai kingdoms of Sukhothai, Lanna, and Lan Xang (now Laos) were on the rise.
However, a century later, the power of Sukhothai was overshadowed by the new Kingdom of Ayutthaya, established in the mid-14th century in the lower Chao Phraya River or Menam area.
European traders arrived in the early 16th century, beginning with the envoy of Portuguese duke Afonso de Albuquerque in 1511, followed by the French, Dutch, and English.