Work conducted at Tulum continued with that of Sylvanus Morley and George P. Howe, beginning in 1913. They worked to restore and open the public beaches. The work was continued by the Carnegie Institution from 1916 to 1922, Samuel Lothrop in 1924 who also mapped the site, Miguel Ángel Fernández in the late 1930s and early 1940s, William Sanders in 1956, and then later in the 1970s by Arthur G. Miller. Through these later investigations done by Sanders and Miller, it has been determined that Tulum was occupied during the late Postclassic period around AD 1200. The site continued to be occupied until contact with the Spanish was made in the early 16th century. By the end of the 16th century, the site was abandoned completely.