The history of Mindoro dates back before the Spanish time. Records have it that Chinese traders were known to be trading with Mindoro merchants. Trade relations with China where Mindoro was known as "Mai’ started when certain traders from "Mai" brought valuable merchandise to Canton in 892 A.D. The geographic proximity of the island to China Sea had made possible the establisment of such relations with Chinese merchantmen long before the first Europeans came to the Philippines.

Historians claimed that China-Mindoro relations must have been earlier than 892 A.D.., the year when the first ship from Mindoro was recorded to have sailed for China. It is believed that the first inhabitants of Mindoro were the Indonesians who came to the island 8,000 to 3,000 years ago. After the Indonesians, the Malays came from Southeast Asia around 200 B. C. The Malays were believed to have extensive cultural contract with India, China and Arabia long before they settled in Philippine Archipilago

Mindoro, formerly called Mait, was known to Chinese traders even before the coming of the Spanish. In 1570, the Spanish began to explore the island and named it "Mina de Oro" (mine of gold) after finding some of the precious metal, though no major gold discoveries were ever made. Missionaries became active around Ilin Island off the southern tip, Lubang Island off the northern tip, and Mamburao. Moro raids later forced them to abandon these places. In 1754, the Muslims established strongholds in Mamburao and Balete (near Sablayan). From there, they launched raids against nearby settlements. An expedition sent by Governor Simon de Anda put an end to these raids.

In the early years, Mindoro was administered as part of Bonbon, now Batangas. Early in the 17th century, the island was separated from Bonbon and organized into a corregimiento. In 1902 the island of Lubang, which was formerly a part of Cavite, was annexed to Mindoro. In the same year Mindoro and Lubang were annexed to Marinduque when the latter became a regular province. Mindoro became a regular province in 1921. On June 13, 1950, under Republic Act No. 505, Mindoro was divided into two provinces, Occidental Mindoro and Oriental Mindoro.

The plains of Occidental Mindoro are inhabited by the Tagalogs and the remote forested interior by the Mangyans. Extensive tribal settlements of Mangyans in the province belong to such sub-groups as the Iraya, Alangan, Tadyawan, Buhid, Hanunuo, and Bangon. The Mangyans are simple people. They were once coastal dwellers driven into the mountains to avoid religious conversion by the Spaniards, raids by Moro pirates, and the influx of recent migrants. They now lead a semi-nomadic existence. Mangyans live in loose clusters of up to 20 bamboo huts with thatched roofs and raised floors. They sometimes are away from their families for many weeks in search of food. Men wear a loincloth of pounded bark while the women have a coil of woven nito, a sturdy black vine, and rattan around their hips. Mangyans practice animism and are superstitious.

Much like the province of Oriental Mindoro to which it belongs, Puerto Galera is very rich in history. Literally meaning "Port of Galleons," it became popular among seafarers during the prosperous years of the galleon trade starting with Chinese traders from the 10th century. Owing to its excellent natural harbor - which until now is considered one of the most beautiful and safest in the world - Puerto Galera became a regular stopover for merchant vessels sailing along the important trade routes of the Near East, Indian coast, Indo-Chinese coast, China, Philippines, Sumatra, and Java.

The local community was founded by the Spanish with the consecration of the Church in 1572. The Muelle Bay area, in particular, was used extensively for dock repairs and as a safe anchorage for all types of sailing vessels. Here, too, a lot of merchant ships docked to trade with the natives. Puerto Galera was such important port that some historians even believe the name "Mindoro" was derived from Minolo, one of Puerto Galera's old settlements.

There are claims also that 16th century references to Mindoro often only meant the harbor of Minolo. Also spelled Minoro, Minolo was a small coastal settlement northwest of the Poblacion of present-day Puerto Galera. Then the center of trading, Chinese merchants bartered with natives of Minolo, exchanging glazed porcelains for gold, jade, corals, shells, birds, rattan, and other forest products that were abundant in the island. An excavation of an ancient grave site near Minolo lends proof to this - the antiques unearthed from the grave sites were traced back to the 10th and 15th centuries, mostly from China, Thailand, and Vietnam.

By the 17th century, under its Spanish colonizers, the island of Mindoro was organized into a coregimiento, with Puerto Galera as the capital. The seat of government remained here throughout the Spanish and American rules, up until 1903.

After more than two centuries, the capital of the province was transferred to Calapan (now a city and the present capital of Oriental Mindoro), which was geographically blessed with wide agricultural lands. Puerto Galera was then annexed to Calapan as a barrio. Finally, on December 7, 1927, the Philippine Congress passed Act 3415 creating the independent municipality of Puerto Galera.

Epigraphs referring to two historical landmarks have now become major tourist attractions in Puerto Galera - the commemoration Cross for Cañonero Mariveles and the Black Rice display-board, both in Muelle Pier.

When Puerto Galera was made capital of Mindoro, it was originally located in Barrio Lagundian. But the frequency of the Moro attacks forced the Spaniards not only to transfer the seat government to its present site, but also to build watchtowers and station battleship that guarded the waters of Puerto Galera was the Cañonero Mariveles, which sunk due to a violent storm in 1879. To remember the battleships, a wooden cross was built at Muelle Pier with the following inscription: "Ultima tierra que pesarou los tripolantes del cañoneros Marivelles el 18 de Noviembre de 1879." One of the greatest relics of the past century, this Cross was renovated in 1938 by a Spaniard named Luis Gomez y Sotto.

Aside form introducing tools to increase farm productivity, the Spaniards also built a rice granary in Puerto Galera to stash grains ready for shipment. This storage is believed to have caught fire in the late of 18th century, and a huge volume of palay (rice grains) were burned and tossed into the sea. It would decompose and eventually vanish. But for some magical reason, the burned rice grains were preserved by seawaters. To this day, handfuls of whole charcoal-black rice grains continue to appear on the banks of Muelle Bay, mysteriously carried by the waves with the changing of tides. A huge glass case collecting them now stands along the tricycle terminal on Muelle Pier.