Archaeologists in Mexico have confirmed that a shipwreck discovered off the coast of the Yucatan peninsula once carried captured Mayans who were sold into slavery.

It is the first Mayan slave ship ever discovered, according to Mexico's National Institute of Anthropology and History (INAH), which made the announcement on Tuesday.

The paddle wheel steamboat, known as "La Unión," was discovered by archaeologists in the Gulf of Mexico two nautical miles from Sisal in 2017. But it took three years of research to confirm that it was a Mayan slave ship.

La Unión illegally captured and transported about 25 to 30 Mayans monthly to Cuba, where they were forced to work in sugarcane fields between 1855 and 1861. This was during the rebellion known as the Caste War, according to INAH.