Question: After the emergence of which empire, the Akkad came to designate the area between Nippur and Sippar?

Context paragraphs:
Carl Benjamin: Carl Benjamin (born September 1, 1979), also known by his pseudonym Sargon of Akkad, is an English YouTube commentator.  Benjamin's alias is taken from the first ruler of the Akkadian Empire, Sargon of Akkad.

Ancient Mesopotamian units of measurement: Ancient Mesopotamian units of measurement originated in the loosely organized city-states of Early Dynastic Sumer.  Each city, kingdom and trade guild had its own standards until the formation of the Akkadian Empire when Sargon of Akkad issued a common standard.  This standard was improved by Naram-Sin, but fell into disuse after the Akkadian Empire dissolved.  The standard of Naram-Sin was readopted in the Ur III period by the Nanše Hymn which reduced a plethora of multiple standards to a few agreed upon common groupings.  Successors to Sumerian civilization including the Babylonians, Assyrians, and Persians continued to use these groupings.  Akkado-Sumerian metrology has been reconstructed by applying statistical methods to compare Sumerian architecture, architectural plans, and issued official standards such as Statue B of Gudea and the bronze cubit of Nippur.

Enshakushanna: Enshakushanna (or En-shag-kush-ana, Enukduanna, En-Shakansha-Ana) was a king of Uruk in the later 3rd millennium BC who is named on the Sumerian king list, which states his reign to have been 60 years.  He conquered Hamazi, Akkad, Kish, and Nippur, claiming hegemony over all of Sumer.  He adopted the Sumerian title "en ki-en-gi lugal kalam-ma", which may be translated as "lord of Sumer and king of all the land" (or possibly as ""en" of the region of Uruk and "lugal" of the region of Ur"), and could correspond to the later title "lugal ki-en-gi ki-uri" "King of Sumer and Akkad" that eventually came to signify kingship over Mesopotamia as a whole.

List of kings of Akkad: This is a list of kings of Akkad, also rendered as Agade.  Akkad was a major empire in ancient Mesopotamia in the 3rd millennium BCE.  The area covered by the kingdom is now located in the region of present-day Iraq, eastern Turkey and northern Syria.

Paradynasteuon: The paradynasteuōn (Greek: παραδυναστεύων , "the one who rules beside") was a term used, especially in the Byzantine Empire, to designate a ruler's favorite, often raised to the position of chief minister.  Probably deriving from Thucydides, it was used in the later Roman Empire for people with great authority.  It was not an official title or position, but the term was extensively used by chroniclers such as Theophanes the Confessor or Theophanes Continuatus to designate an emperor's closest aide and chief minister.  It gained greater currency during the Komnenian period and continued to be used by historians of the Palaiologan period, although the more technical term of "mesazōn" ("mediator"), which eventually came to correspond to an actual office, had largely replaced it.

Rimush: Rimush (or Rimuš) was the second king of the Akkadian Empire.  He was the son of Sargon of Akkad and Queen Tashlultum.  He was succeeded by his brother Manishtushu, and was an uncle of Naram-Sin of Akkad.

Naram-Sin of Akkad: Naram-Sin (also transcribed Narām-Sîn or Naram-Suen, meaning "Beloved of Sin"; reigned c. 2254–2218 BC,) was a ruler of the Akkadian Empire, the third successor and grandson of King Sargon of Akkad.  Under Naram-Sin the empire reached its maximum strength.  He was the first Mesopotamian king known to have claimed divinity for himself, taking the title "God of Akkad", and one of the first (following the earlier Lugal-Anne-Mundu) to claim the title "King of the Four Quarters, King of the Universe".

Akkadian Empire: The Akkadian Empire was the first ancient Semitic-speaking empire of Mesopotamia, centered in the city of Akkad and its surrounding region, also called Akkad in ancient Mesopotamia in the Bible.  The empire united Akkadian and Sumerian speakers under one rule.  The Akkadian Empire exercised influence across Mesopotamia, the Levant, and Anatolia, sending military expeditions as far south as Dilmun and Magan (modern Bahrain and Oman) in the Arabian Peninsula.

Battle of Opis: The Battle of Opis, fought in September 539 BC, was a major engagement between the armies of Persia under Cyrus the Great and the Neo-Babylonian Empire under Nabonidus during the Persian invasion of Mesopotamia.  At the time, Babylonia was the last major power in western Asia that was not yet under Persian control.  The battle was fought in or near the strategic riverside city of Opis, north of the capital Babylon.  It resulted in a decisive victory for the Persians.  A few days later, the city of Sippar surrendered to the Persians and Cyrus's forces entered Babylon apparently without a fight.  Cyrus was subsequently proclaimed king of Babylonia and its subject territories, thus ending the independence of Babylon and incorporating the Babylonian Empire into the greater Persian Empire.

Akkad (region): Akkad is the historical name of a region in northern Mesopotamia around the city of Akkad, probably near the confluence of the Diyala with the Tigris.  After the emergence of the Akkadian Empire, Akkad came to designate the area between Nippur and Sippar.  During the first millennium BCE, Akkad was used as a name not only for the northern half of Babylonia, but also for Sumer.  The meaning of the name is unknown.

Supporting paragraphs: Akkadian Empire Akkad (region)
Answer: Akkadian Empire