Tiglath-Pileser III
However, when Rusa I inherited the throne, the Assyrians had regrouped under their new king Tiglath-Pileser III and had rapidly become a formidable foe, once more expanding their empire. The Assyrians repeatedly invaded Urartu, thus forcing Rusa I to spend the early years of his reign fighting the forces of Assyria. The conflict took a heavy toll on Urartu, particularly on its economy. After suffering numerous reverses, Urartu lost the territory it had annexed under Sarduri II to Tiglath-Pileser III, and was forced to pay tribute to Assyria.