Belshazzar is not recorded in history. Herodotus (400's BC) and Xenophon (300's BC) knew nothing of Belshazzar. If the book of Daniel had been written in the 200's BC then Nabonidus would be recorded as the last king instead of Belshazzar. Multiple sources in archaeology have now confirmed Belshazzar's existence and his position as king of Babylon along with his father. So, Daniel’s written account that we have today was written by an eyewitness of these events.
"Great Banquet" - Persian kings are recorded as entertaining 15,000, Alexander had 10,000 guests at a wedding, Xerxes had a large gathering from his empire for 180 days (6 months). Both Greek historians Herodotus and Xenophon write about this same party the night Babylon fell.
The date is October 12, 539 BC according to the "Nabonidus Chronicle.” This Nabonidus Chronicle (Details HERE and HERE. Photo HERE and HERE) records the Babylonians had suffered a major defeat a few days before this party of October 12, 539 BC. One of the statements says, “The king (Nabonidus) was in Tema; the king’s son (Belshazzar), courtiers and army were in Babylonia.” The Nabonidus Cylinder also records King Nabonidus in these words: “Belshazzar the firstborn son, the offspring of my heart.”
The reason for the feast appears to be an annual celebration of the Babylonians/Chaldeans. While Belshezzar used this event to boost morale, the Persians took advantage of the opportunity to enter a city distracted by the celebration of a holiday. The city was protected by water which gave them a vast supply. Heroditus says they had enough stored food to last for several years.
Belshazzar’s command "to bring the gold . . . .from the temple in Jerusalem" would have been taboo in this culture because it violated holy things from another religion. Belshazzar was drunk.
The women were present and were being encouraged to drink. The holy vessels were used to toast the pagan gods. The king was showing his superiority over the gods (which included YHWH) whom Babylon had conquered
Belshazzar may have been mocking:
a. Daniel's prophecy of Babylon's fall to Persia in 8:1-4 and 8:15-20
b. Isaiah prophecy of Cyrus' coming in Isaiah 44:28 and 45:1
The word translated "hand" refers to the palm of the hand. The wall was "plaster" made of chalk or lime. Excavations of the throne room in 1899 revealed that the walls were washed over with white gypsum. This banquet room has possibly been located and excavated.
Mene - Numbered - Belshazzar's evil life and rule would soon be over
Tekel - Weighed - "wanting" or "lacking, deficient" in moral worth
Parsin - Divided - his kingdom would be divided into pieces or destroyed, dissolved
Herodotus and Xenophon tell us that the two sets of double walls extending for 17 miles and 40 feet high, but the water was diverted into a swamp and the soldiers waded through the river under the walls. The ancient historians also record that Gobryas, Cyrus' commander, led soldiers into the palace where they found the king (Belshazzar) holding a dagger to kill himself. The king and attendants were overpowered and killed. King Nabonidus was later captured and deported.