For 10 points, Samuel Huntington wrote about the "Clash" of what entities?
These entities title an 11 book series that includes the Pulitzer-Prize winning Rousseau and Revolution, a series by Will and Ariel Durant. Michio Kaku's book Parallel Worlds proposes an extension to a system for classifying these entities developed by Rudolf Kardashev that groups them into Type I, II, and III varieties. These entities are said to arise through a process of "challenge and response" according to Arnold Toynbee, and are analogized to (*) superorganisms with predictable lifespans in the magnum opus of Oswald Spengler. Ukraine is considered to be "cleft" because it sits on the border of the "Orthodox" example of one of these according to a 1993 article in Foreign Affairs. Places like the Indus River Valley, the Yellow River Valley, and the Fertile Crescent are often referred to as the "cradle" of examples of these entities. For 10 points, Samuel Huntington wrote about the "Clash" of what entities?
These entities title an 11 book series that includes the Pulitzer-Prize winning Rousseau and Revolution, a series by Will and Ariel Durant.
civilizations [accept The Story of Civilization or cradle of civilization] 