Hittites is the conventional English-language term for an ancient people who spoke an Indo-European language and established a kingdom centered in Hattusa (Hittite URUḪattuša) in northern Anatolia from the 18th century BC. In the 14th century BC, the Hittite Kingdom was at its height, encompassing central Anatolia, south-western Syria as far as Ugarit, and upper Mesopotamia. After 1180 BC, amid general turmoil in the Levant associated with the sudden arrival of the Sea Peoples, the kingdom disintegrated into several independent "Neo-Hittite" city-states, some of which survived until as late as the 8th century BC. The history of the Hittite civilization is known mostly from cuneiform texts found in the area of their kingdom, and from diplomatic and commercial correspondence found in various archives in Egypt and the Middle East.
It is generally assumed that the Hittites came into Anatolia some time before 2000 BC. While their earlier location is disputed, there has been strong evidence for more than a century that the home of the Indo-Europeans in the fourth and third millennia was in the Pontic Steppe, present day Ukraine around the Sea of Azov. The Hittites and other members of the Anatolian family then came from the north, possibly along the Caspian Sea. Their movement into the region set off a Near East mass migration sometime around 1900 BC The dominant inhabitants in central Anatolia at the time were Hattians. There were also Assyrian colonies in the country; it was from these that the Hittites adopted the cuneiform script. It took some time before the Hittites established themselves, as is clear from some of the texts included here. For several centuries there were separate Hittite groups, usually centered around various cities. But then strong rulers with their center in Boğazköy succeeded in bringing these together and conquering large parts of central Anatolia to establish the Hittite kingdom.
Around 2000 BC, the region centered in Hattusa, that would later become the core of the Hittite kingdom, was inhabited by people with a distinct culture who spoke a non-Indo-European language. The name "Hattic" is used by Anatolianists to distinguish this language from the Indo-European Hittite language that appeared on the scene at the beginning of the 2nd millennium BC and became the administrative language of the Hittite kingdom over the next six or seven centuries. As noted above, "Hittite" is a modern convention for referring to this language. The native term was Nesili, i.e. "In the language of Neša".
The early Hittites, whose prior whereabouts are unknown, borrowed heavily from the pre-existing Hattian culture, and also from that of the Assyrian traders — in particular, the cuneiform writing and the use of cylindrical seals.
Since Hattic continued to be used in the Hittite kingdom for religious purposes, and there is substantial continuity between the two cultures, it is not known whether the Hattic speakers — the Hattians— were displaced by the speakers of Hittite, were absorbed by them, or just adopted their language.
The early history of the Hittite kingdom is known through tablets that may first have been written in the 17th century BC but survived only as copies made in the 14th and 13th centuries BC. These tablets, known collectively as the Anitta text, begin by telling how Pithana the king of Kussara or Kussar (a small city-state yet to be identified by archaeologists) conquered the neighbouring city of Neša (Kanesh). However, the real subject of these tablets is Pithana's son Anitta, who continued where his father left off and conquered several neighbouring cities, including Hattusa and Zalpuwa (Zalpa).
The founding of the Hittite Kingdom is attributed to either Labarna I or Hattusili I (it is debated whether this is the same person), who conquered the area south and north of Hattusa. Hattusili campaigned as far as the kingdom of Yamkhad in Syria, where he attacked, but did not capture, its capital of Aleppo. His heir, Mursili I, conquered that city in a campaign conducted in 1595 BC. Also in 1595 BC, Mursili I (or Murshilish I) conducted a great raid down the Euphrates River and captured Mari and Babylon. However, the Hittite campaigns caused internal dissension which forced a withdrawal of troops to the Hittite homelands. Throughout the remainder of the sixteenth century BC, the Hittite kings were held to their homelnads by dynastic quarrels and warfare with the Hurrian's--their neighbors to the east. Although the campaigns into Syria and Mesopotamia may be responsible for the reintroduction of cuneiform writing into Anatolia, since the Hittite script is quite different from the script of the preceding Assyrian Colony period.
Mursili continued the conquests of Hattusili. Mursili's conquests reached Mesopotamia and even ransacked Babylon itself in 1531 BC. Rather than incorporate Babylonia into Hittite domains, Mursili seems to have instead turned control Babylonia over to his Kassite allies, who were to rule it for the next four centuries. This lengthy campaign, however, strained the resources of Hatti, and left the capital in a state of near-anarchy. Mursili was assassinated shortly after his return home, and the Hittite Kingdom was plunged into chaos. The Hurrians, a people living in the mountainous region along the upper Tigris and Euphrates rivers took advantage of the situation to seize Aleppo and the surrounding areas for themselves, as well as the coastal region of Adaniya, renaming it Kizzuwatna (later Cilicia).
Following this, the Hittites entered a weak phase of obscure records, insignificant rulers, and reduced area of control. This pattern of expansion under strong kings followed by contraction under weaker ones, was to be repeated over and over again throughout the Hittite Kingdom's 500-year history, making events during the waning periods difficult to reconstruct with much precision. The political instability of these years of the Old Hittite Kingdom, can be explained in part by the nature of the Hittite kingship at that time. During the Old Hittite Kingdom period prior to 1400 BC, the king of the Hittites was not viewed by the Hittite citizenry as a "living god," like the Pharaohs of Egypt. Rather the Hittite king was viewed as a first among equals. Only in the later period of the Hittite Empire from 1400 BC until 1200 BC, did the kingship of the Hittites become more centralized and powerful.
The next monarch of any note following Mursili I was Telepinu (ca. 1500 BC), who won a few victories to the southwest, apparently by allying himself with one Hurrian state (Kizzuwatna) against another (Mitanni).
Telepinu's reign marked the end of the "Old Kingdom" and the beginning of the lengthy weak phase known as the "Middle Kingdom." The period of the 15th century BC is largely unknown with very sparse surviving records. The Middle Kingdom is not so much an independent phase of Hittite history as a period of transition between the Old and New Kingdoms.
Almost nothing is known about the History of the Hittites in this period. The last monarch of the Old kingdom, Telepinu, reigned until about 1500 BC. The "Middle Kingdom" is the following period of obscurity, lasting for about 70 years, until the emergence of the New Kingdom. This period is called the "Hittite Empire period," proper, and dates from the reign of Tudhaliya I from ca. 1430 BC.
One innovation that can be credited to these early Hittite rulers is the practice of conducting treaties and alliances with neighboring states; the Hittites were thus among the earliest known pioneers in the art of international politics and diplomacy.
With the reign of Tudhaliya I (who may actually not have been the first of that name; see also Tudhaliya), the Hittite Kingdom re-emerges from the fog of obscurity. Hittite civilization entered the perioid of time called the "Hittite Empire period." Many changes were afoot during this time, not the least of which was a strengthening of the kingship. Settlement of the Hittites progressed in the Empire period. However, the Hittite people tended to settle in the older lands of south Anatolia rather than the lands of the Aegean. As this settlement progressed, treaties were signed with neighboring peoples. During the Hittite Empire period the kingship became heriditary and the king took on a "superhuman aura" and began to be referred to by the Hittite citizens as "My Sun." The kings of the Empire period began acting as a high priest for the whole kingdom--making an annual tour of the Hittite holy cities, conducting festivals and supervising the upkeep of the sanctuaries.
During his reign (c. 1400 BC), King Tudhaliya I, again allied with Kizzuwatna, the vanquished the Hurrian states of Aleppo and Mitanni, and expanded to the west at the expense of Arzawa (a Luwian state).
Another weak phase followed Tudhaliya I, and the Hittites' enemies from all directions were able to advance even to Hattusa and raze it. However, the Kingdom recovered its former glory under Suppiluliuma I (c. 1350 BC), who again conquered Aleppo, reduced Mitanni to tribute under his son-in-law, and defeated Carchemish, another Syrian city-state. With his own sons placed over of all of these new conquests, Babylonia still in the hands of the Kassites, and Assyria only newly independent with the crushing of Mitanni, this left Suppiluliuma the supreme power broker outside of Egypt, and it was not long before even that country was seeking an alliance by marriage of another of his sons with the widow of Tutankhamen. Unfortunately, that son was evidently murdered before reaching his destination, and this alliance was never consummated.
After Suppiluliuma I, and a very brief reign by his eldest son, another son, Mursili II became king (c. 1330). Having inherited a position of strength in the east, Mursili was able to turn his attention to the west, where he attacked Arzawa and a city known as Millawanda in the coastal land of Ahhiyawa. Many recent scholars have surmised that Millawanda in Ahhiyawa is likely a reference to Miletus and Achaea known to Greek history, though there are a small number who have disputed this connection.
Hittite prosperity was mostly dependent on control of the trade routes and metal sources. Because of the importance of Northern Syria to the vital routes linking the Cilician gates with Mesopotamia, defense of this area was crucial, and was soon put to the test by Egyptian expansion under Pharaoh Rameses II. The outcome of the battle is uncertain, though it seems that the timely arrival of Egyptian reinforcements prevented total Hittite victory. The Egyptians forced the Hittites to take refuge in the fortress of Kadesh, but their own losses prevented them from sustaining a siege. This battle took place in the 5th year of Rameses (c.1274 BC by the most commonly used chronology).
After this date, the power of the Hittites began to decline yet again because of the rising power of the Assyrians. The Assyrians had seized the opportunity to vanquish Mitanni and expand to the Euphrates while Muwatalli was preoccupied with the Egyptians. Assyria now posed just as great a threat to Hittite trade routes as Egypt ever had. Muwatalli's son, Urhi-Teshub, took the throne and ruled as king for 7 years as Mursili III before being ousted by his uncle, Hattusili III after a brief civil war. In response to increasing Assyrian encroachments along the frontier, he concluded a peace and alliance with Rameses II, presenting his daughter's hand in marriage to the Pharaoh. The "Treaty of Kadesh", one of the oldest completely surviving treaties in history, fixed their mutual boundaries in Canaan, and was signed in the 21st year of Rameses (c. 1258 BC).Terms of this treaty included the marriage of one of the Hittite princesses to the Pharaoh Rameses. 
Hattusili's son, Tudhaliya IV, was the last strong Hittite king able to keep the Assyrians out of Syria and even temporarily annex the island of Cyprus. The very last king, Suppiluliuma II also managed to win some victories, including a naval battle against the Sea Peoples off the coast of Cyprus. But it was too little and too late. The Sea Peoples had already begun their push down the Mediterranean coastline, starting from the Aegean, and continuing all the way to Philistia—taking Cilicia and Cyprus away from the Hittites en route and cutting off their coveted trade routes. This left the Hittite homelands vulnerable to attack from all directions, and Hattusa was burnt to the ground sometime around 1180 BC following a combined onslaught from Kaskas and Bryges. The Hittite Kingdom thus vanished from historical records.
By 1160 BC, the political situation in Asia Minor looked vastly different from how it had only 25 years earlier. In that year, the Assyrians were dealing with the Mushku pressing into northernmost Mesopotamia from the Anatolian highlands, and the Gasga people, the Hittites' old enemies from the northern hill-country between Hatti and the Black Sea, seem to have joined them soon after. The Mushku or Mushki had apparently overrun Cappadocia from the West, with recently discovered epigraphic evidence confirming their origins as the Balkan "Bryges" tribe, forced out by the Macedonians.
Although the Hittites disappeared from Anatolia at this point, there emerged a number of so-called Neo-Hittite kingdoms in Anatolia and northern Syria. They were the successors of the Hittite Kingdom. The most notable Syrian Neo-Hittite kingdoms were those at Carchemish and Milid (near the later Melitene). These Neo-Hittite Kingdoms gradually fell under the control of the Assyrians, who conquered Carchemish during the reign of Sargon II in the late 8th century BC, and Milid several decades later.
A large and powerful state known as Tabal occupied much of southern Anatolia. Known as Gk. Τιβαρηνοί Tibarenoi, Lat. Tibareni, Thobeles in Josephus, their language may have been Luwian, testified to by monuments written using Luwian hieroglyphics.
Ultimately, both Luwian hieroglyphs and cuneiform were rendered obsolete by a new innovation, the alphabet, which seems to have entered Anatolia simultaneously from the Aegean (with the Bryges, who changed their name to Phrygians), and from the Phoenicians and neighboring peoples in Syria.