The colorful term "Bamboo Curtain" was derived from "Iron Curtain", a term used widely in Europe from the 1940s to the 1980s to refer to that region's Communist boundaries. It was used less often than "Iron Curtain" in part because while the latter remained relatively static for over 40 years, the "Bamboo Curtain" shifted frequently and was somewhat less precise. It was also a less accurate description of the political situation in Asia because of the lack of cohesion within the East Asian Communist Bloc, which resulted in the Sino-Soviet split. During the Cold War, Communist governments in Mongolia, Vietnam, and Laos were allies of the Soviet Union, though they sometimes cooperated with China, while Pol Pot's Cambodian regime was loyal to China. After the Korean War, North Korea avoided taking sides between the Soviets and China. (Since the end of a Communist bloc in Asia, North Korea remains on good terms with both Russia and China, although relations between the countries have been strained in modern times.)