The earliest Cambodian references to Phú Quốc (known as Koh Tral) are found in royal documents dated 1615[citation needed], however no one has offered compelling evidence that Khmers have ever had a substantial presence there, or that a state exercised authority.

[6] Around 1680, Phú Quốc was part of the Principality of Hà Tiên, a maritime polity founded by Chinese merchant and explorer Mạc Cửu under the patronage of the Cambodian king.

After War of the second fall of Ayutthaya, Mạc Thiên Tứ tried to install Prince Chao Chui (เจ้าจุ้ย, Chiêu Thúy in Vietnamese) as the new Siamese king, but was defeated by Taksin.

[10] Hà Tiên was completely devastated by Siamese troops in 1771, Mạc Thiên Tứ had flee to Trấn Giang (modern Cần Thơ).

[10] The French missionary Pigneau de Behaine used the island as a base during the 1760s and 1780s to shelter Nguyễn Ánh, who was hunted by the Tây Sơn army.

[6] The British envoy John Crawfurd en route to Siam from Singapore in 1822 made a stop at Phú Quốc which he transcribed as Phu-kok in March.

A few spots here and there on the coasts only are inhabited, -the rest being, as usual, covered with a great forest, which we were told, contained abundance of deer, hogs, wild buffaloes, and oxen, but no leopards or tigers...

The inhabitants of Phu-kok were described to us as amounting to four to five thousand, all of the true Cochinchinese race, with the exception of a few occasional Chinese sojourners.

They grow no species of corn and their husbandry is confined to a few coarse fruits and esculent green vegetables and farinaceous roots..."[12]Western records in 1856 again mentioned the island: "... King Ang Duong (of Cambodia) apprize Mr. de Montigny, French envoy in visit to Bangkok, through the intermediary of Bishop Miche, his intention to yield Phú Quốc to France.

"[15]While the war between Vietnam and France was about to begin, Ang Duong sent another letter, dated November 25, 1856, to Napoleon III to warn him about Cambodian claims on the lower Cochinchina region: the Cambodian king listed provinces and islands, including Phú Quốc, as being parts of Vietnam for several years or decades (in the case of Saigon some 200 years).

Ang Duong asked the French emperor to not annex any part of these territories because, as he wrote, despite this relatively long Vietnamese rule, they remained Cambodian lands.

[18] Phú Quốc was located in IV Corps Tactical Zone and was an integral part of South Vietnam's system for detaining enemy prisoners.

A July 1982 agreement between Vietnam and The People's Republic of Kampuchea ostensibly settled the dispute; however, the island is still the object of irredentist sentiments.

Phú Quốc Island is mainly composed of sedimentary rocks from the Mesozoic and Cenozoic age, including heterogeneous conglomerate composition, layering thick, quartz pebbles, silica, limestone, rhyolite and felsite.

The island name is coveted and abused in the fish sauce industry that local producers have been fighting for the protection of its appellation of origin.

[25] The pearl farming activity began more than 20 years ago when Australian and Japanese experts arrived to develop the industry with advanced technology.

[31] The island's monsoonal sub-equatorial climate is characterized by distinct rainy (April to November) and dry seasons (December to March).

The sea around Phú Quốc is one of the richest fishing grounds in all of Vietnam, and the aim of the protected area is to secure coral reef zones, seagrass beds, and mangrove forests, all key spawning and nursery grounds for aquatic species, including blue swimming crabs.

[35][36] Plastic waste is a growing problem in Phú Quốc, and the local community has organized clean-up efforts.