Tulum was a major staging ground for the Caribbean Assassins. The Mayan Mentor, Ah Tabai, trained many Assassins, such as Mary Read and Adéwalé, there. The Assassin turncoat known as Duncan Walpole was briefly trained by him too.
After the pirate Edward Kenway unwittingly sold the location of a number of Assassin bureaus to the Templars, Tulum was attacked and many of the Assassins were either killed or captured. Those that survived were eventually released by Edward in recompense for his actions.