Anthropologist Herbert Phillips of the University of California, Berkeley, claimed that Seidenfaden "probably had more first-hand knowledge of the culture and history of the Thai and related peoples than did any other European of this century," whose ethnological interpretations nonetheless amounted to "informed prejudice.

In April 1907, after Siam was forced by the French to give up on the regions of Battambang, Srisophon and Siemrep in Cambodia, Captain Erik Seidenfaden was put in charge of nine huge convoys moving the Siamese Governor-general Phraya Chhum Abhaiwongse Kathathom (1861–1922) and his belongings out.

The convoy, which travelled 300 kilometres west under constant rains consisted of 1,700 ox carts, of which 1,350 requisitioned from the local farmers of Prachinburi in Siam, their final destination, took three months.

Apart from the Governor-general's life guard of 40 men, armed with rifles and swords, Seidenfaden had 100 gendarmes with him, many if not most Danish, many suffering from cholera and beriberi, and a gang of robbers was said to be at the heels of the convoy.

In 1927 Seidenfaden wrote a Guide to Bangkok for the Royal State Railway Department.,[1][8] which was reprinted several times, including in 1984 by Oxford University Press, as it had become a standard work describing many of Thailand's buddhist temples.

The exhibition sought to include all the traditional, national costumes of the many branches of the Thai people which Seidenfaden noticed were fast disappearing often to be replaced by more modern fashions.

[7] Despite having no formal scholarly training, he was an "enthusiastic amateur ethnographer” and a pioneer of Thai studies, which saw him examine and document national and regional ethnicity as well as work to preserve these disappearing cultures.