Tianxia in the context of "Tian"

The Mandate of Heaven (Chinese: 天命; pinyin: Tiānmìng; Wade–Giles: T'ien-ming; lit. 'Heaven's command') is a Chinese political doctrine that was used in Ancient China and Imperial China to legitimize the rule of the king or emperor of China. According to this doctrine, Heaven (天, Tian) bestows its mandate on a virtuous ruler, called the Son of Heaven (天子, Tianzi), who is the supreme universal monarch that will rule the world (天下, Tianxia; "[all] under heaven"). If a ruler was overthrown, this was interpreted as an indication that the ruler and his dynasty were unworthy and had lost the Mandate. It was also a common belief that natural disasters such as famine and flood were divine retributions bearing signs of Heaven's displeasure with the ruler, so there would often be revolts following major disasters as the people saw these calamities as signs that the Mandate of Heaven had been withdrawn.

The Mandate of Heaven does not require a legitimate ruler to be of noble birth. Chinese dynasties such as the Han and Ming were founded by men of common origins, but they were seen as having succeeded because they had gained the Mandate of Heaven. Retaining the mandate is contingent on the just and able performance of the rulers and their heirs.

The Shanhai Pass (simplified Chinese: 山海关; traditional Chinese: 山海關; pinyin: Shānhǎi Guān; lit. 'Mountain Sea Pass') is a major fortified gateway at the eastern end of the Great Wall of China and one of its most crucial fortifications, as the pass commands the narrowest choke point in the strategic Liaoxi Corridor, an elongated coastal plain between the Yan Mountains foothills and the Bohai Sea, which is the only easily traversable landway between North and Northeast China. It is located in present-day Shanhaiguan District, Qinhuangdao, Hebei province, on the east bank of the Shi River, with defensive walls stretching from the Yan Mountains all the way to the shores of the Liaodong Bay.

Throughout Chinese history, garrisons around the pass served as frontline defensive outposts against raids and incursions into the North China Plain by various non-Sinitic ethnic groups from the Northeast (also known as Manchuria since the 19th century), including the Dongyi, Donghu (Xianbei and Wuhuan), Khitan and Jurchen (Manchus). The current Shanhai Pass was built during the early Ming dynasty as the easternmost fortification of the Ming Great Wall, and was extensively reinforced after Yongle Emperor moved the capital from Nanjing to Beijing following the Jingnan campaign, making it the most important defensive barrier in all of China, as it shielded the heartland region around the imperial capital. The pass' strategic location dictated that without mounting a costly direct siege, the only way an invading army can get past the pass' defense was to circumvent it around the north through a few treacherously narrow mountain passes deep within the Yan Mountains, which would make it very difficult to maintain supply lines and thus any sizeable invasions. This defensive significance therefore earned the pass the famous nickname "Greatest Pass Under Heaven" (天下第一关).

The Chinese monarchs were the rulers of China during Ancient and Imperial periods. The earliest rulers in traditional Chinese historiography are of mythological origin, and followed by the Xia dynasty of highly uncertain and contested historicity. During the subsequent Shang (c. 1600–1046 BCE) and Zhou (1046–256 BCE) dynasties, rulers were referred to as Wang 王, meaning king. China was fully united for the first time by Qin Shi Huang (r. 259–210 BCE), who established the first Imperial dynasty, adopting the title Huangdi (皇帝), meaning Emperor, which remained in use until the Imperial system's fall in 1912.

At no point during Ancient or Imperial China was there a formalized means to confer legitimate succession between rulers. From the Zhou dynasty onwards, monarchs justified their reigns by claiming the Mandate of Heaven (天命; Tiānmìng). The mandate held that a ruler and their successors had permission from the heavens to rule as long as they did so effectively. It also declared a ruler the Son of Heaven (天子; Tiānzǐ), giving them the right to rule "all under heaven" (天下; Tiānxià). Given the Mandate's subjective nature, rulers also utilized a variety of methods to retain support and justify their accession. This ranged from military enforcement, political patronage, establishing peace and solidity, institutional reform, and historical revisionism to legitimize the dissolution of previous dynasties and their own succession. For most of Imperial China, the wuxing (五行; "Five Elements") philosophical scheme was also central to justify dynastic succession.

Wang Gungwu AO, CBE (simplified Chinese: 王赓武; traditional Chinese: 王賡武; pinyin: Wáng Gēngwǔ; born 1930), also written Wang Gung Wu, is a Chinese Australian historian, sinologist, and writer specialising in the history of China and Southeast Asia. He has studied and written about the Chinese diaspora. An expert on the Chinese tianxia ("all under heaven") concept, he was the first to suggest its application to the contemporary world as an American tianxia. He is the recipient of many honours and awards, including the Singapore Literature Prize at age 91.

Imperial titles were used in various historical Korean states before the 14th century and at the turn of the 20th century: Early Korean states used "great king", "greatest king", and "holy king"; later Korean states used "emperor". Korean monarchs who used imperial titles had political and religious authority over a realm or domain. The Chinese concept of tianxia, pronounced "cheonha" in Korean, was variously adopted and adapted to Korean views of the world from period to period.

Emperor at home, king abroad was a system of conducting relations between states within the Chinese cultural sphere. Rulers of lesser regimes would adopt the title of emperor (皇帝; or other equivalents) and/or other imperial titles domestically, and adopt the title of king (王; or other equivalents) when dealing with the dominant Chinese regime. Instead of using the styles Imperial Majesty and Majesty (陛下), rulers of lesser realms were styled as Highness (殿下). This system was applicable to Japan, Korea and Vietnam, as well as less powerful Chinese states, among others.

As China was a hegemonic power in East Asia for a large part of history, surrounding states were compelled to pay tribute to Chinese emperors in exchange for peace and political legitimacy. In this system, lesser regimes accepted the suzerainty of the dominant Chinese power and acknowledged the Chinese emperor as their nominal overlord. Since Chinese emperors claimed to be the Son of Heaven and held supremacy over all under Heaven, rulers of lesser regimes were to use titles subordinate to emperor. The same doctrine also maintained that there could only be one emperor at any given time.