Although mathematical innovation stagnated in Europe after the fall of the Roman Empire, scholars in southern Asia and the Middle East continued to preserve the mathematical writings of the Greeks and contributed new ideas to arithmetic, algebra, geometry, and trigonometry, as well as astronomy and physics. The five centuries from CE 1300 to 1800 marked the end of a rich period of cultural, mathematical, and scientific advancements in China, India, and Arabic countries, while witnessing new intellectual life in Europe and the Western Hemisphere. "The Age of Genius" acquaints middle and high school students with the lives and contributions of 10 intriguing but perhaps lesser-known mathematical pioneers of this time. Included here, for example, is a portrait of 14th-century Iranian mathematician Ghiyath al-Din Jamshid Mas'ud al-Kashi, who developed and improved methods for approximating numerical values, and introduced geometrical methods for determining areas and volumes of architectural domes, arches, and vaults.