Gulf of Thailand in the context of "Crab claw sail"

The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by South China, in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Philippines (mainly Luzon, Mindoro, and Palawan), and in the south by Borneo, eastern Sumatra, and the Bangka Belitung Islands, encompassing an area of around 3,500,000 km (1,400,000 sq mi). It communicates with the East China Sea via the Taiwan Strait, the Philippine Sea via the Luzon Strait, the Sulu Sea via the straits around Palawan, the Java Sea via the Karimata and Bangka Straits, and directly with the Gulf of Thailand. Additionally, the Gulf of Tonkin is part of the South China Sea.

$3.4 trillion of the world's $16 trillion maritime shipping passed through the South China Sea in 2016. Oil and natural gas reserves have been found in the area. The Western Central Pacific accounted for 14% of the world's commercial fishing in 2010.

Cambodia, officially the Kingdom of Cambodia, is a country in Mainland Southeast Asia. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline along the Gulf of Thailand in the southwest. It spans an area of 181,035 square kilometres (69,898 square miles), dominated by a low-lying plain and the confluence of the Mekong river and Tonlé Sap, Southeast Asia's largest lake. It is dominated by a tropical climate. Cambodia has a population of about 17 million people, the majority of which are ethnically Khmer. Its capital and most populous city is Phnom Penh, followed by Siem Reap and Battambang.

In 802 AD, Jayavarman II declared himself king, uniting the warring Khmer princes of Chenla under the name "Kambuja". This marked the beginning of the Khmer Empire. The Indianised kingdom facilitated the spread of first Hinduism and then Buddhism to Southeast Asia and undertook religious infrastructural projects throughout the region, the most famous of which is Angkor Wat. In the 15th century, it began a decline in power until, in 1863, Cambodia became a French protectorate. Following Japanese occupation during World War II, Cambodia declared independence from France in 1953. The Vietnam War embroiled the country in civil war during the 1960s, culminating in a 1970 coup which installed the US-aligned Khmer Republic and the takeover of the communist Khmer Rouge in 1975. The Khmer Rouge ruled the country and carried out the Cambodian genocide from 1975 until 1979, until they were ousted during the Cambodian–Vietnamese War. Peace was restored by the 1991 Paris Peace Accords and subsequent United Nations peacekeeping mission, establishing a new constitution, holding the 1993 general election, and ending long-term insurgencies. The 1997 coup d'état consolidated power under Prime Minister Hun Sen and the Cambodian People's Party (CPP).

Thailand, officially the Kingdom of Thailand, and formerly known as Siam until 1939, is a country located in mainland Southeast Asia. It shares land borders with Myanmar to the west and northwest, Laos to the east and northeast, Cambodia to the southeast, and Malaysia to the south. Its maritime boundaries include the Gulf of Thailand and the Andaman Sea, as well as maritime borders with Vietnam, Indonesia, and India. Thailand has a population of nearly 66 million people, covers an area of approximately 513,115 km (198,115 sq mi). The country's capital and largest city is Bangkok.

Archaeological evidence indicates that humans have inhabited the area of present-day Thailand for at least 40,000 years. Indigenous ethnic groups include the Mon, Khmer, and Malay people. The Tai people are believed to have originated from the Điện Biên Phủ region since the 5th century and began migrating into the territory of modern Thailand between the 8th and 10th centuries origin of the Tai people. During the classical historical period, major kingdoms such as Sukhothai, Lan Na, and Ayutthaya were established. The Sukhothai Kingdom is regarded as the beginning of Thai history, while the Ayutthaya Kingdom, founded in 1350 CE, became a regional power replacing the Khmer Empire. European contact began in 1511 CE when Portuguese envoys arrived in Ayutthaya. The Ayutthaya Kingdom flourished until its complete destruction during the 1765–1767 Burmese–Siamese War by the Burmese forces under the Konbaung dynasty in 1767.

Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of Mainland Southeast Asia. With an area of about 331,000 square kilometres (128,000 sq mi) and a population of over 100 million, it is the world's 15th-most populous country. One of two communist states in Southeast Asia, Vietnam is bordered by China to the north, Laos and Cambodia to the west, the Gulf of Thailand to the southwest, and the South China Sea to the east; it also shares maritime borders with Thailand, Malaysia, and Indonesia to the south and southwest, the Philippines to the east, and China to the northeast. Its capital is Hanoi, while its largest city is Ho Chi Minh City.

Vietnam was inhabited by the Paleolithic age, with states established in the first millennium BC on the Red River Delta in modern-day northern Vietnam. The Han dynasty annexed northern and central Vietnam, which were subsequently under Chinese rule from 111 BC until the first dynasty emerged in 939. Successive monarchical dynasties absorbed Chinese influences through Confucianism and Buddhism, and expanded southward to the Mekong Delta, conquering Champa. During most of the 17th and 18th centuries, Vietnam was effectively divided into two domains of Đàng Trong and Đàng Ngoài. The Nguyễn—the last imperial dynasty—surrendered to France in 1883. In 1887, its territory was integrated into French Indochina as three separate regions. In the immediate aftermath of World War II, the Viet Minh, a coalition front led by the communist revolutionary Ho Chi Minh, launched the August Revolution and declared Vietnam's independence from the Empire of Japan in 1945.

The Kra Isthmus (Thai: คอคอดกระ, pronounced [kʰɔ̄ː kʰɔ̂ːt kràʔ]; Malay: Segenting Kra), also called the Isthmus of Kra in Thailand, is the narrowest part of the Malay Peninsula. The western part of the isthmus belongs to Ranong province and the eastern part to Chumphon province, both in Southern Thailand. At its narrowest point, between the Thai cities of Kra Buri and Chumphon, the coastal distance between the Andaman Sea and the Gulf of Thailand is only 44 km (27 mi).

The Kra Isthmus marks the boundary between two sections of the mountain chain which runs from Tibet through the Malay peninsula. The southern part is the Phuket Range, which is a continuation of the Tenasserim Hills, extending further northwards for over 400 km (250 mi) beyond the Three Pagodas Pass.

The Chao Phraya River (Thai: แม่น้ำเจ้าพระยา) is the major river in Thailand, with its low alluvial plain forming the centre of the country. It flows through Bangkok and then into the Gulf of Thailand.