Belshazzar began to reign around 553 BC as co-regent with his father, Nabonidus, who had begun to reign around 556 BC. Although Belshazzar was officially second-in-command to Nabonidus from 553 to 539 BC, he appears to have been the active ruler of Babylon during this time.

Daniel 7:1-14 - around 553 BC - Daniel's Vision of Four Beasts

Daniel 7:15-28 - The Vision is Explained

Daniel 8:1-14 - around 551 BC - Daniel's Vision of a Ram and Goat

Daniel 8:15-27 - Gabriel Explains the Vision

The following events took place the night before the Medes and Persians conquered Babylon in october of 539 BC

Daniel 5:1-12 - 539 BC - The Writing on the Wall

Daniel Explains the Writing - Daniel 5:13-31