The Hilly Flanks are the upland areas surrounding the Fertile Crescent of Southwest Asia, including the foothills of the Zagros Mountains, the Taurus Mountains, and the highland parts of the Levant.
The term was coined by Robert Braidwood in 1948. He proposed that the Neolithic Revolution began in the Hilly Flanks because these areas received enough rainfall for agriculture without irrigation. He also observed that many of the wild progenitors of domesticated crops had their natural habitats in the Hilly Flanks, as did wild sheep and goat. His theory was in opposition to the oasis theory of V. Gordon Childe, which placed the origins of agriculture in well-watered desert refugia such as Mesopotamia. Ultimately, archaeological investigations proved Braidwood correct.