Belshazzar, co-regent of the Babylonian Empire, watched as these words were supernaturally written on the palace wall the very night his kingdom fell (probably October 13, 539 BC). What a frightening experience that must have been for him and his festive guests!
Each of the words the fingers inscribed on the wall is a measure of weight (like our ounce, pound, and ton, or milligram, gram, and kilogram). The basic Babylonian unit of weight was the gold shekel (tekel in this verse). The mena equalled 50 shekels; the upharsin (half a mena) equalled 25. The four words, therefore, stood for: mena, 50 shekels; mena, 50 shekels; tekel, 1 shekel; upharsin, 25 shekels. The total equalled 126 shekels.
In addition, each shekel can be divided into even smaller units (as a pound can be divided into ounces, for example). The shekel was equal to 20 gerahs (Ezekiel 45:12). The 126 shekels of Daniel 5:25 is equivalent to 2,520 gerahs.
The words of the handwriting on the wall symbolize that God had "weighed" Belshazzar's kingdom and found it wanting (Daniel 5:26-27). The empire would be given to the Medes and the Persians, who entered and captured the city of Babylon that same night. God was about to punish Belshazzar's realm for 2,520 years.
This is confirmed by another prophecy found in Daniel 4. Through Daniel, God told King Nebuchadnezzar that a total of "seven times" of punishment would befall Babylon (verses 16, 25). In prophecy, a "time" equals a year of 360 days. This can be seen by noting that 3 1/2 "times" equals 42 months or 1,260 days (Revelation 12:6, 14; 13:5). "Seven times," therefore, equals 2,520 days, and Nebuchadnezzar himself spent seven years without his human reason, living like a beast (Daniel 4:31-37). In certain prophecies, however, such as in Daniel 5, each day represents a year in fulfillment (Numbers 14:34; Ezekiel 4:6). These back-to-back prophecies in Daniel 4-5 show the type (Nebuchadnezzar) and anti-type (Babylon) fulfillment of many biblical prophecies. This is the prophetic principle of duality.
So, then, from the experiences of both Nebuchadnezzar and Belshazzar, it is evident Babylon would be punished for a period of 2,520 years.
After that time, it will rise again, as symbolized by the tree that sprouted and grew after the iron band was removed (Daniel 4:10-16, 19-26). Since this period of 2,520 years expired in 1982, we can expect to see the rise of modern Babylon in this present generation (also foretold in Revelation 18). It may even now be forming as the final revival of the Roman Empire in Europe.