The Euphrates river was first mentioned by Moses in Genesis 2. The River begins up near the traditional landing site of Noah's Ark; so it can be readily understood that the "Pharat" (a loan word Hebrew word related to the "Aryan" origin) was the model used to describe the original river in Eden. There is no way of knowing if the present river is the same as the original, though the new beginning after the flood is used by many to "identify" the location of the garden of Eden.
The ancient civilizations created at Babel (Babylon) and Ur were located on the Euphrates within a few hundred years of the Global Flood. Terah and his family migrated from Ur to Haran, and it was from the banks of the Euphrates that Abraham saw the land which God had promised to him. Generations before, descendants of Ham - Canaan and Mitsra (father of the Mitsraim - that is Egypt) - founded civilizations based on knowledge gleamed from Babel choosing the lesser Jordan River and the greater Nile River respectively upon which to build. Spending a third of his life on the Nile, Moses still remembered the Euphrates when he wrote down his history of the world.
Years later, the later Babylon would rise up along these banks to defeat the Assyrians (who shared the River) and overrun Judah generations after the Assyrians had destroyed o. In the end we learn in the Revelation that this great River will be dried up to allow the "kings of the east" a pathway to over-run what is left of "Western" Civilization (the final version of "Babylon.")