The Gwich'in people, a Northern Athabaskan group also lived in the area in the last 1000 years, moving south of the park in historic times. The Alaskan interior was not explored until the late 19th century, shortly before discovery of gold in the Klondike brought prospectors to Alaska. Some encampments of explorers and survey parties have been identified in the park. A few small mining operations were established in the early 20th century, never amounting to much. The park's name dates to 1929, when wilderness activist Bob Marshall, exploring the North Fork of the Koyukuk River, encountered a pair of mountains (Frigid Crags and Boreal Mountain), one on each side of the river. He christened this portal the "Gates of the Arctic." Marshall spent time in Wiseman during the early 1930s, publishing an account of the place in his 1933 book "Arctic Village". In the 1940s writer and researcher Olaus Murie proposed that Alaskan lands be preserved. Proposals for a national park in the Brooks Range first emerged in the 1960s, and in 1968 a National Park Service survey team recommended the establishment of a park in the area. That year, Secretary of the Interior Stewart Udall recommended to President Lyndon B. Johnson that Johnson use the Antiquities Act to proclaim a national monument in the Brooks Range and other Alaskan locations, but Johnson declined. During the 1970s the Alaska Native Claims Settlement Act (ANCSA) prompted serious examination of the disposition of lands held by the federal government. A series of bills were considered to deal with conservation land proposals authorized under ANCSA, but the legislation that would become the Alaska National Interest Lands Conservation Act (ANILCA) was held up in Congress in the late 1970s. Consequently, on December 1, 1978 President Jimmy Carter used the Antiquities Act to proclaim much of the proposed new Alaskan parklands as national monuments, including Gates of the Arctic National Monument. In 1980 Congress passed ANILCA, and the monument became Gates of the Arctic National Park and Preserve on December 2, 1980.