 Part of the plot revolves around the bubonic plague, a disease with a terrible history in Europe in the Middle Ages when it was called the Black Death and worldwide in the 19th century.The disease is still present in Arizona, Utah, Colorado, New Mexico and California in the United States.Jano was found on lands that had been shared by Hopi and Navajo peoples, but a federal law had placed the area within the borders of the Navajo Nation.