Numa Denis Fustel de Coulanges was a French historian and scholar. He is known mainly for his 1864 book, The Ancient City, in which he argued that ancient societies, such as those of Greece and Rome, were primarily based around religion, rather than politics or economics. This idea had a big influence on the way historians think about ancient cultures. Fustel de Coulanges was an important figure in the development of sociology, and his work is still studied today.