American Sinologist and historian Edwin O. Reischauer also grouped China, Korea, and Japan into a cultural sphere that he called the "Sinic world", a group of centralized states that share a Confucian ethical philosophy. Reischauer states that this culture originated in Northern China, comparing the relationship between Northern China and East Asia to that of Greco-Roman civilization and Europe. The elites of East Asia were tied together through a common written language based on Chinese characters, much in the way that Latin had functioned in Europe.