After the death of Assurbanipal in 627 BC, the Neo-Assyrian empire entered a period of instability caused by fighting between Sin-shar-ishkun and his brother Assur-etil-ilani.
After a few years of war, the Babylonians expelled the Assyrian forces from their territory.
The situation changed drastically in 616 BC, when the Medes attacked the Assyrian empire.
The fall of Tarbiṣu occurred when the Median army, led by Cyaxares, attacked and conquered the city.
In the aftermath, the Medes went further and decisively defeated the Assyrians at the battle of Assur.