The Ortoiroid people were the second wave of human settlers of the Caribbean who began their migration into the Antilles around 2000 BCE They were preceded by the Casimiroid peoples (~4190-2165 BCE). They are believed to have originated in the Orinoco valley in South America, migrating to the Antilles from Trinidad and Tobago to Puerto Rico. The name "Ortoiroid" comes from Ortoire, a shell midden site in southeast Trinidad.
The Ortoiroid are believed to have developed in South America before moving to the West Indies. The earliest radiocarbon date for the Ortoiroid is 5230 BCE from Trinidad.
The two earliest Ortoiroid sites in Trinidad are the Banwari Trace and at St. John's Road, South Oropouche, which date back at least to 5500 BCE. At this time, Trinidad might have still been connected to the South American mainland.
The majority of archaeological sites associated with the Ortoiroid are found near or on the coasts. Tobago has at least one Ortoiroid site, Martinique has two, and Antigua has 24 Ortoiroid shell-midden sites. Ortoiroid peoples settled on St. Kitts from 2000 BCE to 400 BCE.
In the north, two distinct Ortoiroid subcultures have been identified: the Coroso culture, which flourished from 1500 BCE–200 CE, and the Krum Bay culture, which spanned 1500—200 BCE. The Coroso people lived in Puerto Rico, where the oldest known site is the Angostura site, dating from 4000 BCE. The Krum Bay people lived in the Virgin Islands. Krum Bay culture, which emerged between 800 BCE and 225 BCE, also extended to St. Thomas.
The Ortoiroid are considered the first settlers of the archipelago of Puerto Rico; however, recent reexamination of date, artifact, and agricultural evidence and of assumptions about culture has suggested a more complex picture.