Where did God bind the four powerful demonic beings?

Les explains that God confined four powerful demonic beings in the area of the Euphrates River. These beings had been under Satan's rule. He suggests this may have happened when God scattered the human race at the Tower of Babel, or possibly later after Babylon fell to the Medes and Persians, when some of the high priests of these pagan religions fled. Les also points out that the Euphrates River is the great boundary between east and west, with east of the Euphrates predominantly pagan idolatrous religions and west including Judaism, Muhammadism, and Christianity.