History of Guam

The history of Guam starts with the early arrival around 2000 BC of Austronesian people known today as the Chamorro Peoples. The Chamorus then developed a "pre-contact" society, that was colonized by the Spanish in the 17th century. The present American rule of the island began with the 1898 Spanish–American War. Guam's history of colonialism is the longest among the Pacific islands.

The Mariana Islands were the first islands settled by humans in Remote Oceania. Incidentally it is also the first and the longest of the ocean-crossing voyages of the Austronesian peoples into Remote Oceania, and is separate from the later Polynesian settlement of the rest of Remote Oceania. They were first settled around 1500 to 1400 BC by migrants departing from the Philippines.

Archeological studies of human activity on the islands has revealed potteries with red-slipped, circle-stamped and punctate-stamped designs found in the Mariana Islands dating between 1500 and 1400 BC. These artifacts show similar aesthetics to pottery found in Northern and Central Philippines, the Nagsabaran (Cagayan Valley) pottery, which flourished during the period between 2000 and 1300 BC.

Comparative and historical linguistics also indicate that the Chamoru language is most closely related to the Indonesian Malayan subfamily of the Austronesian languages, instead of the Oceanic subfamily of the languages of the rest of Remote Oceania.

Mitchondrial DNA and whole genome sequencing of the Chamoru people strongly support Philippine ancestry. Genetic analysis of pre-Latte period skeletons in Guam also show that they do not have Melanesian ancestry which rules out origins from the Bismarck Archipelago, New Guinea, or eastern Indonesia. The Lapita culture itself (the ancestral branch of the Polynesian migrations) is younger than the first settlement of the Marianas (the earliest Lapita artifacts are dated to around 1350 to 1300 BCE), indicating that they originated from separate migration voyages.

Nevertheless, DNA analysis also shows a close genetic relationship between ancient settlers of the Marianas and early Lapita settlers in the Bismarck Archipelago. This may indicate that both the Lapita culture and the Marianas were settled by direct migrations from the Philippines, or that early settlers from the Marianas voyaged further southwards into the Bismarcks and reconnected with the Lapita people.

The Marianas also later established contact and received migrations from the Caroline Islands at around the first millennium CE. This brought new pottery styles, language, genes, and the hybrid Polynesian breadfruit.

The period 900 to 1700 CE of the Marianas, immediately before and during the Spanish colonization, is known as the Latte period. It is characterized by rapid cultural change, most notably by the massive megalithic latte stones (also spelled latde or latti). These were composed of the haligi pillars capped with another stone called tasa (which prevented rodents from climbing the posts). These served as supports for the rest of the structure which was made of wood. Remains of structures made with similar wooden posts have also been found. Human graves have also been found in front of latte structures. The Latte period was also characterized by the introduction of rice agriculture, which is unique in the pre-contact Pacific Islands.