Chang and Eng Bunker (May 11, 1811 – January 17, 1874) were the conjoined twin

Conjoined twins

Conjoined twins are identical twins whose bodies are joined in utero. A rare phenomenon, the occurrence is estimated to range from 1 in 50,000 births to 1 in 100,000 births, with a somewhat higher incidence in Southwest Asia and Africa. Approximately half are stillborn, and a smaller fraction of...

 brothers whose condition and birthplace became the basis for the term "Siamese twins".
The Bunker brothers were born on May 11, 1811 in Siam (now Thailand

Thailand

Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

), in the province of Samutsongkram

Samut Songkhram Province

Samut Songkhram ) is one of the central provinces of Thailand.Neighboring provinces are Phetchaburi, Ratchaburi and Samut Sakhon. Local people call Samut Songkhram Mae Klong. The province is the smallest of all Thai provinces areawise...

, to a fisherman and a mother (Nok or นาก [Nak] in Thai). Because of their Chinese heritage (as they were born from a Thai Chinese

Thai Chinese

The Thai Chinese are an overseas Chinese community who live in Thailand. Thailand is home to the largest, oldest, most prominent, and most integrated overseas Chinese community in the world with a population of approximately 9.5 million people...

 father and Chinese-Malay

Malay people

Malays are an ethnic group of Austronesian people predominantly inhabiting the Malay Peninsula, including the southernmost parts of Thailand, the east coast of Sumatra, the coast of Borneo, and the smaller islands which lie between these locations...

 mother.), they were known as the "Chinese Twins" in Siam.