The Three Kingdoms period (traditional Chinese: 三國時代; simplified Chinese: 三国时代; pinyin: Sānguó shídài) was a period in Chinese history, part of an era of disunity called the "Six Dynasties" following immediately the loss of de facto power of the Han Dynasty rulers. In a strict academic sense it refers to the period between the foundation of the state of Wei in 220 AD and the conquest of the state Wu by the Jin Dynasty in 280.  However, many Chinese historians and laymen extend the starting point of this period back to the Yellow Turban Rebellion in 184.

The Three Kingdoms (traditional Chinese: 三國; simplified Chinese: 三国; pinyin: Sānguó) were Wei (魏), Shu (蜀), and Wu (吳). To further distinguish these states from other historical Chinese states of the same name, historians add a relevant character: Wei is also known as Cao Wei (曹魏), Shu is also known as Shu Han (蜀漢), and Wu is also known as Dong Wu or Eastern Wu (東吳). The term "Three Kingdoms" itself is something of a mistranslation, since each state was eventually headed not by kings, but by an emperor who claimed legitimate succession from the Han Dynasty. Although the translation "Three Empires" is more contextually accurate, the term "Three Kingdoms" has become standard among sinologists.

Guan Yu (died 219) was a general serving under the warlord Liu Bei during the late Eastern Han Dynasty of China. He played a significant role in the civil war that led to the collapse of the Han Dynasty and the establishment of the state of Shu Han during the Three Kingdoms period, of which Liu Bei was the first emperor.

As one of the best known Chinese historical figures throughout East Asia, Guan's true life stories have largely given way to fictionalized ones, mostly found in the historical novel Romance of the Three Kingdoms or passed down the generations, in which his deeds and moral qualities have been lionized. Guan is respected as an epitome of loyalty and righteousness.

Guan was deified as early as the Sui Dynasty and is still worshipped by many Chinese people today, especially in southern China, Taiwan, and Hong Kong and their descendants overseas. He is a figure in Chinese folk religion, popular Confucianism, Taoism, and Chinese Buddhism, and small shrines to Guan are almost ubiquitous in traditional Chinese shops and restaurants.