La Laguna. July 28, 1571.

The history of the province of Laguna, and that of the Southern Tagalog region, dates as far back as 900 AD. The Laguna Copperplate Inscription is the oldest known written document found in the Philippines, which talks of its subject being released from a debt to the King of Tondo. Pre-Hispanic settlement in the area can be dated to prehistoric times, as evidenced in the names of towns such as Pila, Laguna, whose name can be traced to the straight mounds of dirt that form the boundaries of the rice paddy, or Pilapil.

A prominent figure during the time of pre-Hispanic contact is Gat Pangil, a chieftain in the area. The towns of Bay, Pangil and Pakil were reputed to have once been a part of his domain, although accounts vary on who exactly Gat Pangil was.

The Province of Laguna, which was formerly called La Laguna and La Provincia de la Laguna de Bay, was named after Laguna de Bay, the body of water that forms its northern boundary. Laguna de Bay, in turn, was named after the town of Bay, the first provincial capital. Captain Juan de Salcedo with a band of one hundred Spanish-Mexican soldiers conquered the province and its surrounding regions for Spain in July 28, 1571. The province of La Laguna comprised the modern province of Laguna, as well as parts of what is now known as Rizal and Quezon.

In 1577, the Franciscan missionaries arrived in Manila, and in 1578 they started evangelizing Laguna, Morong (now Rizal), Tayabas (now Quezon) and the Bicol Peninsula. Juan de Plasencia and Diego de Oropesa were the earliest Franciscans sent to these places. From 1580, the towns of Bay, Caliraya, Majayjay, Nagcarlan, Liliw, Pila, Santa Cruz, Lumban, Pangil and Siniloan were founded. During the time of Governor-General Gomez Perez Dasmarinas, the province of La Laguna was divided into encomiendas:

By 1591, there were approximately 48,400 people living in the province.

Laguna was the site of multiple engagements during the Sangley Rebellion. In 1603, Antonio de Morga relates how the Chinese rebels scattered to three divisions, one of which went to the mountains of San Pablo. Captain Don Luys de Velasco, aided by Spanish and Filipino forces, was successful in pursuing the rebels. Eventually the Chinese were able to kill Luys de Velasco and ten of his men, before securing themselves in San Pablo while waiting for reinforcement from the mainland. On the 20th of October, 1603, Governor-General Pedro Bravo de Acuña then sent Captain Cristoval de Axqueta Menchaca to pursue and crush the rebellion and was successful after twenty days of fighting.

Around this time the hot springs of Los Baños and San Pablo were known to the Spanish, and a hospital was built in the area. By 1622 the hospital was notable enough to be mentioned by the Archbishop of Manila at the time, Miguel García Serrano in his letter to King Philip IV.

In 1639, a second rebellion involving the Chinese occurred, and the rebels fortified themselves in the highlands of Cavinti and Lumban before surrendering in Pagsanjan a year later.

In 1670, a delimitation of borders were made between Lucban, Majayjay and Cavite. The most populous town at that time, Bay, was capital of the province until 1688, when the seat of the provincial government was moved to Pagsanján. Pagsanján would be the provincial seat until 1858 when it was moved once again to Santa Cruz. In 1754, the Province of Laguna and Tayabas were divided, with the Malinao River separating the towns of Majayjay and Lucban.

In 1678, Fray Hernando Cabrera founded San Pablo de los Montes (now San Pablo City) and built a wooden church and convent considered as the best and finest in the province.

Fighting extended to Laguna during the British occupation of Manila between the years of 1762-64. A detachment of British troops under Captain Thomas Backhouse entered the province in search of the silver cargo of the galleon Filipina while Francisco de San Juan led a band of volunteers that fought them in several engagements in and around the then provincial capital of Pagsanjan. Backhouse plundered the town and burned its newly reconstructed church but San Juan succeeded in escaping with the precious hoard to Pampanga where the treasure greatly bolstered the defense effort of Governor-General Simón de Anda y Salazar. For his actions, San Juan was made a brigade commander and alcalde mayor of Tayabas (now Quezon) province.