Polynesian people settled on Easter Island in the first millennium AD, and created a thriving culture, as evidenced by the moai and other artifacts. However, human activity, the introduction of the Polynesian rat and overpopulation led to gradual deforestation and extinction of natural resources, which caused the demise of the Rapa Nui civilization. By the time of European arrival in 1722, the island's population had dropped to 2,000–3,000 from a high of approximately 15,000 just a century earlier. Diseases carried by European sailors and Peruvian slave raiding of the 1860s further reduced the Rapa Nui population, down to 111 in 1877.

Source