 The Median Cyaxares had also recently taken advantage of the anarchy in the Assyrian Empire, while officially still a vassal of Assyria, he took the opportunity to meld the Iranian peoples; the Medes, Persians, Sagartians and Parthians, into a large and powerful Median-dominated force.The Medes, Persians, Parthians, Chaldeans and Babylonians formed an alliance that also included the Scythians and Cimmerians to the north.While Sin-shar-ishkun was fighting both the rebels in Assyria and the Chaldeans and Babylonians in southern Mesopotamia, Cyaxares (hitherto a vassal of Assyria), in alliance with the Scythians and Cimmerians launched a surprise attack on civil-war-bleaguered Assyria in 615 BCE, sacking Kalhu (the Biblical Calah/Nimrud) and taking Arrapkha (modern Kirkuk).