Hopi elders appointed Thomas Banyacya in 1948 as one of four interpreters charged with carrying a warning beyond the Hopi to the wider world, a role he carried out for the rest of his life, including an address to the United Nations General Assembly in 1992 and a meeting with the Dalai Lama. The material he and other Hopi spokespeople released for outside audiences describes this as the Fourth World, reached after three earlier worlds ended in destruction, and sets out two paths open to humanity going forward, a road of technology without spiritual balance leading to ruin, and a road of harmony with the natural world.
Signs said to mark the approach of a period of purification include the arrival of light-skinned people who would claim the land as their own, "cobwebs" strung across the land and sky, and rivers of stone built across the earth, details Hopi spokespeople have themselves matched to European colonisation, telegraph and telephone wires, and paved highways. The most frequently quoted sign describes a "gourd of ashes" that would fall from the sky, capable of boiling the ocean and burning the land for many years, a warning Hopi spokespeople have read since 1945 as a description of nuclear weapons, a reading given particular weight by the Hopi reservation's proximity, within the same state, to the Los Alamos laboratory and the Trinity test site.