John Thomson's 19th-century photography captures an extensive record of Southeast Asia and China, marking him as a pivotal travel photographer. In 1865, Thomson arrived in Siam, now Thailand, where he photographed King Mongkut and his court, city life in Bangkok, and the countryside, before visiting Cambodia's Angkor Wat. His return to London preceded further travels in China from 1868 to 1872, documenting regions like Guangdon, Fujian, and Beijing, as well as the Yangtze river. His work, comprising over 600 glass negatives showcasing remarkable cultural insights, is preserved in London's Wellcome Library.