Sadae

Sadae ("lit." "serving-the-Great," Hangul: 사대 Hanja: ) is a neutral, non-pejorative Korean term which is used in pre-modern contexts. "Sadae" is a Confucian concept, based on filial piety, that describes a reciprocal hierarchical relationship between a senior and a junior, such as a tributary relationship. The term is used as a descriptive label for bilateral foreign relations between Imperial China and Joseon dynasty Korea. Korea's "sadae" toward China was first employed by Silla in the 7th century, but it was not fully implemented until the Confucianization of Korea in the early Joseon dynasty. Korea's "sadae" toward China from the 7th century to the 13th century was only nominal.
Etymology.
The historical term is derived from the Chinese "shi da" (Korean, "sadae") as used by the philosopher Mencius. "Sadae" literally means "dealing with the great" or "serving the great."
The neutral term is distinguished from the pejorative "sadaejuui", which was invented by early 20th century Korean nationalists. The genesis of the term "sadae" arises in the work of the Chinese philosopher Mencius:
 
Overview.
"Sadae" describes a foreign policy characterized by the various ways a small country acknowledges the strength of a greater power like that of China. "Sadae" is made manifest in the actions of the weaker state as it conveys goodwill and respect through its envoys.
The utility of the "sadae" concept in Korea was recognized from the period of Three Kingdoms of Korea to 1895; and it is demonstrated in the relationship of mid-Joseon Korea towards the Ming Dynasty of China. The Joseon Dynasty made every effort to maintain a friendly relationship with Beijing for reasons having to do with realpolitik and with an idealized Confucian worldview. "Sadae" construes China as the center of a Confucian moral universe.
As a foundation of diplomacy, the Joseon kingdom presumed that the Korean state was positioned within a Sinocentristic milieu. The Joseon foreign policy was organized around maintaining stable Joseon-Chinese relations in the period from 1392 through 1895. The concept of "sadae" is contrasted with limited trade relationships or "kyorin" diplomacy (교린정책; "lit." "neighborly relations") which marked Joseon-Japanese relations in this period.
20th century re-interpretation.
The concept of "sadae" was rejected in the writings of polemicist Shin Chaeho and other Korean nationalists in the 20th century. Shin is known for having argued that the "sadae" effectively functioned in two ways:
His revisionist writings sought to deny the relevance of "sadae" as an important element of Korean history.