The next acquisition of Phraortes became Persis, which is mentioned by Herodotus; in one of the Babylonian inscriptions dating to the reign of Nabonides (middle of the 6th century B.C.) the submission of the Persians by the Medes is also mentioned. It could not take place earlier than the 630-s. After these conquests Media and Babylonia began to prepare for the war which led to the destruction of Assyria.

The comparison of cuneiform texts and archaeological data with the evidence provided by Herodotus makes possible to distinguish the second period in the history of Media, to suggest a new scheme for the Median dynasty and to solve the Scythian problem. This period coincides with the reign of Kashtariti (678–625), an outstanding Median ruler whom Herodotus knew under the name of Phraortes. With the acquisition of Urartu this king began the conquest of the Upper Asia, accomplished, according to Herodotus, in the reign of his successor Cyaxares.

3. The alliance of Media and Babylonia in their war against Assyria. By the end of Kashtariti's reign a political alliance between Media and Babylonia, which in 627 B.C. began a new struggle for independence and declared war on Assyria, started to develop. It terminated in a treaty of 614 B.C. between Cyaxares and Nabopolassar. The désintégration of Assyria into two rival kingdoms of Aššur and Nineveh at the beginning of the 620-s was to the advantage of the allies. Although the first campaigns of the Medes against Assyria are testified by the Babylonian sources only in 615 B.C., one can not exclude the possibility of some actions in support of Nabopolassar in his war with Assyria as early as the 620-s. The Babylonian chronicle describing the events of 625 and 623 B.C. does not mention the Medes (the text, however, is not well preserved), though the actions of the Assyrians and of some unknown adversary of theirs coincide with the description by Herodotus of the last campaign of Phraortes and the events following it (I. 102). It is evident that in this case Herodotus became familiar with some primary source of information. He knew that Assyria was split into two parts, he is aware that the Medes fought against Nin/Nineveh. Phraortes was killed in the course of this campaign and his son took revenge on the same kingdom. These events can be tentatively reconstructed on the evidence of the records of 625 and 623 B.C. The suggested earlier Scythian invasion (in the capacity of the unknown enemy of the Chronicle) can be excluded.