A reference to these bandits appears in one of the Tell-el-Amarna letters. Writing to Akhenaton, Ashur-uballit said: "The lands (of Assyria and Egypt) are remote, therefore let our messengers come and go. That your messengers were late in reaching you, (the reason is that) if the Suti had waylaid them, they would have been dead men. For if I had sent them, the Suti would have sent bands to waylay them; therefore I have retained them. My messengers (however), may they not (for this reason) be delayed."[301] Ashur-uballit's grandson extended his Babylonian frontier into Amurru, where he dug wells and erected forts to protect traders. The Kassite aristocracy, however, appear to have entertained towards him a strong dislike, perhaps because he was so closely associated with their hereditary enemies the Assyrians. He had not reigned for long when the embers of rebellion burst into flame and he was murdered in his palace. The Kassites then selected as their king a man of humble origin, named Nazibugash, who was afterwards referred to as "the son of nobody". Ashur-uballit deemed the occasion a fitting one to interfere in the affairs of Babylonia. He suddenly appeared at the capital with a strong army, overawed the Kassites, and seized and slew Nazibugash. Then he set on the throne his great grandson the infant Kurigalzu II, who lived to reign for fifty-five years. Ashur-uballit appears to have died soon after this event. He was succeeded by his son Bel-nirari, who carried on the policy of strengthening and extending the Assyrian empire. For many years he maintained excellent relations with his kinsman Kurigalzu II, but ultimately they came into conflict apparently over disputed territory. A sanguinary battle was fought, in which the Babylonians suffered heavily and were put to rout. A treaty of peace was afterwards arranged, which secured for the Assyrians a further extension of their frontier "from the borders of Mitanni as far as Babylonia". The struggle of the future was to be for the possession of Mesopotamia, so as to secure control over the trade routes. Thus Assyria rose from a petty state in a comparatively brief period to become the rival of Babylonia, at a time when Egypt at the beginning of its Nineteenth Dynasty was endeavouring to win back its lost empire in Syria, and the Hittite empire was being consolidated in the north. CHAPTER XIII. ASTROLOGY AND ASTRONOMY