Portuguese traders introduced firearms as well as New-World goods from the Columbian Exchange, influencing Thai cuisine, language and culture.

[5] Coelho's mission promised to supply guns and ammunition to the Siamese in exchange for Portugal being allowed to establish settlements in Siam, engage with them in trade, and freely practice Christianity.

[15] In 1545, Fernão Mendes Pinto began exploring parts of Siam, where he became the first European to described Phuket in detail, which was called then by Westerners as 'Junk Ceylon'.

This was not exclusive to Siam, as the Portuguese Empire when it was part of the Iberian Union from 1580 to 1640 faced issues with the Dutch, particularly in the Dutch–Portuguese War from 1598 to 1663.

Prasat Thong accepted this request, but Sebastian Moutos d’Avilla decided to escape with the prisoners in September.

[19] Although isolated, Prasat Thong maintained friendly relations with the Dutch who promised to assist him against the Portuguese and Cambodians.

[14] In 1685, Portuguese embassy led by Pero Vaz de Siqueira arrived in Siam from Goa, with the goal of gaining extraterritoriality for Portuguese subjects in Siam and settling disputes with French missionaries of the Paris Foreign Missions Society.

It failed to achieve both goals, but Narai had sent his own mission to Portugal prior to Siqueira's arrival.

[20] Following the fall of Ayutthaya and the establishment of the Chakri dynasty in 1782, the Portuguese were the first Europeans to re-establish relations with Siam, offering guns and ammunition.

As the community at Campos Portugues was destroyed by the Burmese during the 1765-1767 Burmese-Siamese War, the Portuguese diaspora in Siam relocated around three areas: Samsen, Kudi Chin and the Rosary (Talat Noi).

[23] In 1818, Portuguese envoy Carlos Manuel Silveira arrived in Bangkok from Macao where he concluded a commercial agreement between Siam and Portugal.

[24] Also during 1820, Rama II granted land near the Rosary to the Portuguese to build a factory and the residence for Silveira.

[28] Portugal was among the 93 countries granted a 60-day visa-free entry by Prime Minister Srettha Thavisin in July 2024.

[26] The Embassy of Portugal in Bangkok is located along Captain Bush Lane overlooking the Chao Phraya river.

[31] The current ambassador of Portugal to Thailand has been João Bernardo de Oliveira Martins Weinstein since January 2021, receiving his credentials from King Vajiralongkorn in April 2021.

Weinstein had previously served as Portugal's ambassador to Romania, Moldova (non-resident), and Israel.

[34] Majority of these were constructed in the early 1900s following the arrival of Chinese immigrants employed by the Portuguese,[35] and a fire in 1903 which meant many buildings were rebuilt in a Sino-Portuguese style.

Trade with Siam in the 16th and 17th centuries introduced several plants and foods originally from the Americas, such as cassava, chillies, papayas, pineapples, sunflowers, and sweet potatoes.

By 2018, only three families at Kudi Chin made the cake in the traditional way that had been passed down from the original Portuguese settlers.

[26] In 1540, King Chairachathirat rewarded 120 Portuguese mercenaries for their service against the Burmese by granting them land south of Ayutthaya in modern-day Samphao Lom.

Their descendants have gradually assimilated into Thai society, though the community, especially at Kudi Chin, still retains a distinctive identity.