MacLeish acknowledged that he used the expected Nazi takeover of Austria, the Anschluss, as a basis for the work. According to MacLeish, the setting of the play was inspired by the Aztec city of Tenochtitlan, which he had visited in 1929, and in particular the conquest of the city without resistance by Hernán Cortés in 1521, as described by contemporary conquistador Bernal Díaz del Castillo. He also used as inspiration an Aztec myth that told of a woman who had returned from the dead to prophesize the fall of Tenochtitlan just before its conquest.