Thus Nebuchadnezzar completed the work begun by his father, Nabopolassar, and, by the skilful and vigorous prosecution of his campaigns, established the Neo-Babylonian empire on a firm basis, so that its authority was unquestioned from the Persian Gulf to the Egyptian frontier. Of his later campaigns nothing has yet been published, beyond a fragmentary reference to a conflict with Amasis of Egypt in the thirty-seventh year of his reign.[9] Though we do not know the circumstances under which it took place, we may assume that the Babylonian army was again victorious against the Egyptian troops and the Greek mercenaries who fought in their ranks. A tradition is indeed preserved by Josephus that Nebuchadnezzar made Egypt a Babylonian province, and although this is certainly an exaggeration, the evidence suggests that he may well have conducted at least one successful campaign on Egyptian territory. The troubles of Apries in consequence of his ill-advised expedition against Cyrene, followed by the revolt of Amasis and his own deposition and death, may well have furnished the occasion for a successful invasion of the country by Nebuchadnezzar. A very large number of inscriptions have been recovered of the Neo-Babylonian kings, but, unlike the foundation-records of Assyria, they contain no accounts of military expeditions, but confine themselves to commemorating the restoration or erection of temples and palaces in Babylon and the other great cities in the land. Considering his military successes, this is surprising in Nebuchadnezzar's case, and the suggestion has been made that he may have told us so little of his expeditions and battles because they were perhaps undertaken at the bidding of Media as his suzerain.[10] Cyaxares was his kinsman, and the part played by Babylon in the conflict of Media with Lydia may well be explained on that hypothesis. [Illustration: BRONZE DOOR-STEP FROM E-ZIDA, INSCRIBED WITH THE NAME AND TITLES OF NEBUCHADNEZAR ii. Brit. Mus., No. 90851.]