Eastern Cilicia. Niqmepa, who succeeded Idrimi as king of Alalakh, went so far as to ask for help from a Hurrian rival, Shaushtatar of Mitanni, to try and reduce Cilicia's power in the region. It was soon apparent, however, that increased Hittite power would soon prove Niqmepa's efforts to be futile, as the city of Kizzuwatna soon fell to the Hittites, threatening all of Cilicia. Soon after, King Sunassura II was forced to accept vassalization under the Hittites, becoming the last king of ancient Cilicia. After the death of Mursili I, which led to a power struggle among rival claimants to the throne, eventually leading to the collapse of Hittite supremacy, Cilicia appeared to have regained its independence. In the 13th century BC a major population shift occurred as the Sea Peoples overran Cilicia. The Hurrians that resided there deserted the area and moved northeast towards the Taurus Mountains, where they settled in the area of Cappadocia. In the 8th century BC, the region was unified under the rule of the dynasty of Mukšuš, whom the Greeks rendered Mopsos and credited as the founder of Mopsuestia, though the capital was Adana. Mopsuestia's multicultural character is reflected in the bilingual inscriptions of the ninth and eighth centuries, written both in Indo-European hieroglyphic Luwian and West Semitic Phoenician. In the ninth century BC, it became part of Assyria and remained so until the late seventh century BC. Kingdom of Cilicia and Persian period Before the early foundings of the kingdom, Cilicians had to protect themselves from Assyrian domination. After the dissolution of the Neo-Assyrian Empire in 612 BC, they established an independent kingdom from Syria. Given the fact that Cilicia was a strategically significant location, Cilicians were able to expand their kingdom as far north as the Halys River in a short period of time. With these expansions, the Cilician Kingdom became as strong as Babylonia, one of the contemporary powerhouses. The Syennesis dynasty emerged in Cilicia and seemed to have been based in its western part during the reign of Appuašu. The peaceful governance of the Syennesis dynasty sustained the kingdom and prevented the Achaemenid Empire from attacking Lydians after the Achaemenid invasions of Median lands. Appuašu, the son of Syennesis, defended the country against the Babylonian king Neriglissar, whose army reached Cilicia and crossed the Taurus mountain range. The Achaemenids defeated the Lydians, and Appuašu had to recognize the authority