Mithridates I of Parthia vs Nabopolassar

Mithridates I conquered Media and Mesopotamia from the Seleucid Empire, capturing the cities of Ecbatana and Seleucia-on-the-Tigris. These conquests transformed Parthia from a minor kingdom into a major imperial power controlling the Iranian plateau and the Tigris-Euphrates valley.

Mithridates I adopted the Achaemenid title 'King of Kings' (Shahanshah) on his coinage and inscriptions. This act asserted Parthian legitimacy as the successor to the Persian Empire and established the ideological foundation for the Parthian Empire.

Mithridates I defeated and captured the Seleucid king Demetrius II Nicator during a campaign to reclaim the eastern provinces. Demetrius was held captive in Parthia for ten years, during which Mithridates consolidated his conquests.

Nabopolassar, a Chaldean chieftain, led a revolt against Assyrian rule in Babylon. He defeated the Assyrian garrison and declared himself king of Babylon, founding the Neo-Babylonian Empire.

Nabopolassar formed an alliance with Cyaxares, king of the Medes, to jointly attack the Assyrian Empire. This alliance was sealed by the marriage of Nabopolassar's son Nebuchadnezzar II to Cyaxares' daughter Amytis.

Nabopolassar, in alliance with the Medes and Scythians, besieged and sacked the Assyrian capital Nineveh. The city was destroyed, and the Assyrian king Sinsharishkun was killed, effectively ending the Assyrian Empire.

Nabopolassar and his allies defeated the last remnants of the Assyrian army at Harran, where the Assyrians had regrouped with Egyptian support. This victory eliminated any hope of an Assyrian revival and secured Babylonian dominance.