King of the Four Corners of the World (Sumerian: lugal-an-ub-da-limmu-ba, Akkadian: šarru kibrat 'arbaim, šar kibrāti arba'i, or šar kibrāt erbetti), alternatively translated as King of the Four Quarters of the World, King of the Heaven's Four Corners or King of the Four Corners of the Universe and often shortened to simply King of the Four Corners, was a title of great prestige claimed by powerful monarchs in ancient Mesopotamia. Though the term "four corners of the world" does refer to specific geographical places within and near Mesopotamia itself, these places were (at the time the title was first used) thought to represent locations near the actual edges of the world and as such, the title should be interpreted as something equivalent to "King of all the known world", a claim to universal rule over the entire world and everything within it.
The title was first used by Naram-Sin of the Akkadian Empire in the 23rd century BC and was later used by the rulers of the Neo-Sumerian Empire, after which it fell into disuse. It was revived as a title by a number of Assyrian rulers, becoming especially prominent during the Neo-Assyrian Empire. The final ruler to claim the title was the first Persian Achaemenid king, Cyrus the Great, after his conquest of Babylon in 539 BC.
It is possible, at least among Assyrian rulers, that the title of King of the Four Corners was not inherited through normal means. As the title is not attested for all Neo-Assyrian kings and for some only attested several years into their reign it is possible that it might have had to be earned by each king individually, possibly through completing successful military campaigns in all four points of the compass. The similar title of šar kiššatim ("King of Everything" or "King of the Universe"), also with Akkadian origins and attested for some of the Neo-Assyrian kings, may have required seven successful military campaigns. The difference between the exact meaning of the two titles may have been that "King of the Universe" laid claim to the cosmological realm whereas "King of the Four Corners of the World" laid claim to the terrestrial.
Meaning of "Four Corners of the World"
The term "four corners of the world" appears in several ancient mythologies and cosmologies, wherein it roughly corresponds the four points of the compass. In most of these representations, four principal rivers run to these four corners, their water irrigating the four quadrants (or quarters) of the world. In the view of the Mesopotamian Akkadians, the term referred to four regions on the edge of the then known world; Subartu (probably corresponding to the region of Assyria) in the north, Martu (roughly corresponding to modern Syria) in the west, Elam in the east and Sumer in the south. To Naram-Sin of Akkad (r. 2254–2218 BC), the creator of the title, it probably, in geographical terms, expressed his dominion over the regions Elam, Subartu, Amurru and Akkad (representing east, north, west and south respectively).
The term thus covers a somewhat clear geographical region, corresponding to Mesopotamia and its surroundings, but should be understood as referring to the entire known world. At the point in time when the title was first used, the 2200s BC, the Mesopotamians would have equated all of Mesopotamia to the entire world; the region was highly productive, densely populated and was bordered on all sides by seemingly empty and uninhabited lands. A title the like of King of the Four Corners of the World should be taken as meaning that its holder was the ruler of the entire Earth and everything within it. The title can be interpreted as being equivalent to calling oneself "King of all the known world". Thus, the title is an example of merism, combining contrasting concepts to refer to an entirety (the four corners being on the edges of the world and the title referring to them and everything in between).
History
Background (2900–2334 BC)
During the Early Dynastic Period in Mesopotamia (c. 2900–2350 BC), the rulers of the various city-states in the region would often launch invasions into regions and cities far from their own, at most times with negligible consequences for themselves, in order to establish temporary and small empires to either gain of keep a superior position relative to the other city-states. This early empire-building was encouraged as the most powerful monarchs were often rewarded with the most prestigious titles, such as the title of lugal (literally "big man" but often interpreted as "king", probably with military connotations). Most of these early rulers had probably acquired these titles rather than inherited them.