Rattanakosin Kingdom in the context of "Siamese invasion of Kedah"

The French protectorate of Cambodia (Khmer: ប្រទេសកម្ពុជាក្រោមអាណាព្យាបាលបារាំង; French: Protectorat français du Cambodge) refers to the Kingdom of Cambodia when it was a French protectorate within French Indochina, a collection of Southeast Asian protectorates within the French colonial empire. The protectorate was established in 1863 when the Cambodian King Norodom requested the establishment of a French protectorate over his country, meanwhile Siam (modern Thailand) renounced suzerainty over Cambodia and officially recognised the French protectorate on Cambodia.

Cambodia was integrated into the French Indochina union in 1887 along with the French colonies and protectorates in Laos and Vietnam (Cochinchina, Annam, and Tonkin). In 1947, Cambodia was granted self-rule within the French Union and had its protectorate status removed in 1949. Cambodia later gained independence. The day was celebrated as Independence Day on 9 November 1953 led by King Sihanouk and continued to rule as the leader of the nation until he was overthrown in 1970 by the US-led Khmer Republic of Lon Nol in a coup d'état before the rise of Angkar and the Khmer Rouge coming to power on 17 April 1975, following the Fall of Phnom Penh and the end of the Cambodian Civil War.

The Siamese–Vietnamese wars were a series of armed conflicts between the Siamese Ayutthaya Kingdom and Rattanakosin Kingdom and the various dynasties of Vietnam mainly during the 18th and 19th centuries. Several of the wars took place in modern-day Cambodia.

The political, dynastic, and military decline of the Khmer Empire after the 15th century, known as the Post-Angkor Period, left a power vacuum in the Mekong floodplains of central Indochina. United under strong dynastic rule, both Siam to the west and Vietnam to the east sought to achieve hegemony in the lowland region and the Lao mountains. The Siamese introduced — and Vietnam soon followed — the hostage system for Cambodian royals, who were relocated to their courts, actively undermining royal affairs and shaping future Cambodian policies. Eventually, territory was annexed by both powers, who conceived, maintained and supported their favorable Cambodian puppet kings. Actual combat mainly took place on Cambodian territory or on occupied lands. The 19th-century establishment of French Indochina put an end to Vietnamese sovereignty and to Siamese policies of regional expansion. Subsequent clashes of the two countries were not caused by regional rivalry, but must be viewed in the context of the 20th-century imperial policies of foreign great powers and the Cold War.

The Anglo-Siamese Treaty of 1909, also known as the Bangkok Treaty of 1909, was an agreement between the United Kingdom and the Kingdom of Siam (now Thailand). It was signed on 10 March 1909 in Bangkok, with ratifications exchanged in London on 9 July 1909. The treaty established the modern border between Malaysia and Thailand. Areas around modern Pattani, Narathiwat, southern Songkhla, Satun and Yala remained under Thai control, later becoming the site of the South Thailand insurgency.

Under the treaty, Thailand relinquished claims to Kedah (Thai: ไทรบุรี, romanized: Saiburi), Kelantan (กลันตัน, Kalantan), Perlis (ปะลิส, Palit) and Terengganu (ตรังกานู, Trangkanu), which entered the British sphere of influence as protectorates. During World War II, Thailand briefly reclaimed these territories with Japanese permission, but they were returned to British control after the defeat of the Axis powers. These four states, together with Johor, later became known as the Unfederated Malay States, eventually joining the Federation of Malaya and forming part of present-day Malaysia.

The Kingdom of Vientiane was formed in 1707 as a result of the split of the Kingdom of Lan Xang. The kingdom was a Burmese vassal from 1765 to 1779. It then became a Siamese vassal until 1828 when it was annexed by Siam.

The first phase of European colonisation of Southeast Asia took place throughout the 16th and 17th centuries. Where new European powers competing to gain monopoly over the spice trade, as this trade was very valuable to the Europeans due to high demand for various spices such as pepper, cinnamon, nutmeg, and cloves. This demand led to the arrival of Portuguese, Spanish, Dutch, French, and British marine spice traders. Fiercely competitive, the Europeans soon sought to eliminate each other by forcibly taking control of the production centers, trade hubs and vital strategic locations, beginning with the Portuguese acquisition of Malacca in 1511. Throughout the 17th and 18th centuries, conquests focused on ports along the maritime routes, that provided a secure passage of maritime trade. It also allowed foreign rulers to levy taxes and control prices of the highly desired Southeast Asian commodities. By the 19th century, all of Southeast Asia had been forced into the various spheres of influence of European global players except Siam, which had served as a convenient buffer state sandwiched between British Burma and French Indochina. The kings of Siam had to contend with repeated humiliations, accept unequal treaties among massive French and British political interference and territorial losses after the Franco-Siamese crisis of 1893 and the Anglo-Siamese Treaty of 1909.

The second phase of European colonization of Southeast Asia is related to the Industrial Revolution and the rise of powerful nation states in Europe. As the primary motivation for the first phase was the mere accumulation of wealth, the reasons for and degree of European interference during the second phase are dictated by geostrategic rivalries, the need to defend and grow spheres of interest, competition for commercial outlets, long term control of resources and the Southeast Asian economies becoming more closely tied to European industrial and financial affairs by the late 19th century.

The Franco-Siamese crisis of 1893, known in Thailand as the Incident of Rattanakosin Era 112 (Thai: วิกฤตการณ์ ร.ศ. 112,RTGS: wikrittakan roso-roisipsong, [wí krít tàʔ kaːn rɔː sɔ̌ː rɔ́ːj sìp sɔ̌ːŋ]) was a conflict between the French Third Republic and the Kingdom of Siam. Auguste Pavie, French vice-consul in Luang Prabang in 1886, was the chief agent in furthering French interests in Laos. His intrigues, which took advantage of Siamese weakness in the region and periodic invasions by Vietnamese rebels from Tonkin, increased tensions between Bangkok and Paris. The conflict concluded with the Paknam Incident, in which French gunboats sailed up the Chao Phraya River to blockade Bangkok. The Siamese subsequently agreed to cede the area that constitutes most of present-day Laos to France, an act that led to the significant expansion of French Indochina.

This conflict succeeded the Haw wars (1865–1890), in which the Siamese attempted to pacify northern Siam and Tonkin.

Phutthayotfa Chulalok (born Thongduang; 20 March 1737 – 7 September 1809), posthumously honoured as King Phutthayotfa Chulalok the Great, also known by his regnal name Rama I, was the founder of the Rattanakosin Kingdom (now Thailand) and the first King of Siam from the reigning Chakri dynasty. He ascended the throne in 1782, following the deposition of King Taksin of Thonburi. He was also celebrated as the founder of Rattanakosin (now Bangkok) as the new capital of the reunited kingdom.

Rama I, whose given name was Thongduang, was born from a Mon male line descent family, great-grandson of Kosa Pan. His father served in the royal court of the Ayutthaya Kingdom. Thongduang and his younger brother Bunma served King Taksin in wars against the Burmese Konbaung dynasty and helped him in the reunification of Siam. During this time he emerged as Siam's most powerful military leader. Thongduang was the first Somdet Chao Phraya, the highest rank the nobility could attain, equaled to that of royalty. In 1782, he took control of Siam and crowned himself as the monarch. The most famous event in his reign was the Burmese–Siamese War (1785–1786), which was the last major Burmese assault on Siam.