The area known as Croatia today was inhabited throughout the prehistoric period. Fossils of Neanderthals dating to the middle Paleolithic have been unearthed in the area of Krapina and Vindija. More recent (late Mousterian) Neanderthal remains have been discovered in Mujina pećina near the coast.
In the early Neolithic period, the Starčevo, Vučedol and Hvar cultures were scattered around the region. The Iron Age left traces of the Hallstatt culture (early Illyrians) and the La Tène culture (Celts).
Much later the region was settled by Liburnians and Illyrians, and Greek colonies were established on the islands of Vis (by Dionysius I of Syracuse) and Hvar. In 9 AD the territory of today's Croatia became part of the Roman Empire. Emperor Diocletian built a massive palace in Split where he retired from politics in AD 305. During the 5th century the last Roman Emperor Julius Nepos ruled his small empire from Diocletian's Palace before he was killed in AD 480. The early history of Croatia ends with the Avar invasion in the first half of the 7th century and the destruction of almost all Roman towns. Roman survivors retreated to strategically better defended points on the coast, islands and mountains. The modern city of Dubrovnik was founded by those survivors.
The Croats arrived in what is today Croatia in the early 7th century. They organized into two dukedoms; the duchy of Pannonia in the north and the duchy of Littoral Croatia in the south. Emperor Constantine Porphyrogenitus wrote that Porga, duke of the Dalmatian Croats, who had been invited into Dalmatia by Byzantine Emperor Heraclius, sent to Heraclius for Christian teachers. At the request of Heraclius, Pope John IV (640-642) sent Christian teachers and missionaries to the Croatian Provinces. These missionaries converted Porga, and also a great many of the clan that was under his immediate authority, to the Christian faith in 640. The Christianization of the Croats was mostly complete by the 9th century. Both duchies became Frankish vassals in late 8th century, and eventually became independent in the following century.
The first native Croatian ruler recognized by the Pope was duke Branimir, whom Pope John VIII called dux Croatorum ("duke of Croats") in 879. Duke Tomislav of Littoral Croatia was one of the most prominent members of the House of Trpimirović. He united the Croats of Dalmatia and Pannonia into a single Kingdom in 925. Tomislav's state extended from the Adriatic Sea to the Drava river, and from the Raša river to the Drina river. Under his rule, Croatia became one of the most powerful kingdoms in Medieval Europe. Tomislav defeated the invasions of the Arpads in battle and forced them across the Drava. He also annexed a part of Pannonia. This included the area between the rivers Drava, Sava and Kupa, so his Duchy bordered with Bulgaria for a period of time. This was the first time that the two Croatian Realms were united, and all Croats were in one state. The union was later recognised by Byzantium, which gave the royal crown to Stjepan Držislav and papal crown to king Zvonimir. The medieval Croatian kingdom reached its peak during the reign of Kings Petar Krešimir IV (1058–1074) and Zvonimir (1075–1089).
Following the extinction of the Croatian ruling dynasty in 1091, Ladislaus I of Hungary, the brother of Jelena Lijepa, the last Croatian queen, became the king of Croatia. Croatian nobility of the Littoral opposed this crowning, which led to 10 years of war and the recognition of the Hungarian ruler Coloman as the king of Croatia and Hungary in the treaty of 1102 (often referred to as the Pacta conventa). In return, Coloman promised to maintain Croatia as a separate kingdom, not to settle Croatia with Hungarians, to guarantee Croatia's self-governance under a Ban, and to respect all the rights, laws and privileges of the Croatian Kingdom. During this union, the Kingdom of Croatia never lost the right to elect its own king, had the ruling dynasty become extinct. In 1293 and 1403 Croatia chose its own king, but in both cases the Kingdom of Hungary declared war and the union was reestablished.
For the next four centuries, the Kingdom of Croatia was ruled by the Sabor and Bans appointed by the Hungarian king. The Kingdom of Croatia and Slavonia remained a legally distinct constitutional entity, but the advent of a Hungarian king brought about other consequences such as: the introduction of feudalism and the rise of native noble families such as the Frankopans and the Šubićs. The 1273 Congregatio Regni tocius Sclavonie Generalis, the oldest surviving document written by the Croatian parliament, dates from this period. Subsequent kings sought to restore some of their previously lost influence by granting certain privileges to towns.
The first period of personal union between Croatia and Hungary ended in 1526 with the Battle of Mohács and the defeat of Hungarian forces by the Ottomans. After the death of King Louis II, Croatian nobles at the Cetingrad assembly chose the Habsburgs as new rulers of the Kingdom of Croatia, under the condition that they provide the troops and finances required to protect Croatia against the Ottoman Empire.
The city of Dubrovnik was founded in 7th century after Avar and Slavic raiders destroyed the Roman city of Epidaurum. The surviving Roman population escaped to a small island near the coast where they founded a new settlement. During the Fourth Crusade the city fell under control of the Republic of Venice until the 1358 Zadar treaty when Venice, defeated by the Croato-Hungarian kingdom, lost control of Dalmatia and the Republic of Dubrovnik became a vassal of that kingdom. Through the next 450 years the Republic of Dubrovnik would be a vassal of the Ottomans first and then of the Habsburgs. During this time the republic became rich through trade.
The republic became the most important publisher of Croatian literature during the Renaissance and Baroque periods. Aside from poets and writers like Marin Držić and Ivan Gundulić, whose works were important for Croat literature development, the most famous person from the Republic of Dubrovnik was the scientist Ruđer Josip Bošković, who was a member of the Royal Society and the Russian Academy of Sciences. The republic would survive until 1808 when it was annexed by Napoleon. Today the city of Dubrovnik features on the UNESCO World Heritage Site list and is a famous tourist destination.
Shortly after the Battle of Mohács, the Habsburgs unsuccessfully sought to stabilise the borders between the Ottoman Empire and the Kingdom of Croatia by creating a captaincy in Bihać. However, in 1529, the Turks swept through the area and captured Buda and besieged Vienna; an event which brought violence and turmoil to the Croatian border areas (see Ottoman wars in Europe). After the failure of the first military operations, the Kingdom of Croatia was split into civilian and military units in 1553. The latter became Croatian Krajina and Slavonian Krajina and both eventually became parts of the Croatian Military Frontier which was directly under the control of Vienna. Ottoman raids on Croatian territory continued until the Battle of Sisak in 1593, after which the borders stabilised for some time. The kingdom of that time became known as the Reliquiae reliquiarum olim inclyti Regni Croatiae ("The remains of the remains of the once famous Kingdom of Croatia"). An important battle during this time was the Battle of Szigetvár, when 2,300 soldiers under the leadership of ban Nikola Šubić Zrinski held back for two months 100,000 Ottoman soldiers led by Sultan Suleiman the Magnificent, fighting to the last man. Cardinal Richelieu was reported to have called the event "the battle that saved civilization."
During the Great Turkish War, Slavonia was regained but hilly western Bosnia, which had been a part of Croatia until the Ottoman conquest, remained outside Croatian control and the current border, which resembles a crescent or a horseshoe, is a remnant of this historical outcome. The southern part of the 'horseshoe' was created by the Venetian conquest following the Siege of Zara and was defined by the 17-18th century wars with the Ottomans. De jure reason for Venetian expansion was the decision of the king of Croatia, Ladislas of Naples, to sell his rights on Dalmatia to Venice in 1409 .
During more than two centuries of Ottoman Wars, Croatia underwent great demographic changes. The Croats left the riverland areas of Gacka, Lika and Krbava, Moslavina in Slavonia and an area in present day north-western Bosnia to move towards Austria where they remained and the present day Burgenland Croats are direct descendants of these settlers. To replace the fleeing Croats, the Habsburgs called on the Ortodox populations of Bosnia and Serbia to provide military service in Croatian and Slavonian Krajina. The first migration of Orthodox Vlachs, which took on a Serbian identity, occurred during the first part of the 18th century. Serbian populations had slowly started to arrive during the 16th century, with a peak during the Great Serb Migrations of 1690 and 1737-39. The rights and obligations of new populace of the Military frontier were decided with the Statuta Valachorum in 1630.
National revival in Croatia started in 1813 when the bishop of Zagreb Maksimilijan Vrhovac issued a plea for the collection of "national treasures". At the beginning of the 1830s, a group of young Croatian writers gathered in Zagreb and established the Illyrian movement for national renewal and unity of all South Slavs within the Habsburg Monarchy. The most important focus of the Illyrians was the establishment of a standard language as a counter-weight to Hungarian, and the promotion of Croatian literature and official culture. Important members of this movement were Count Janko Drašković, who initiated the movement by writing a pamphlet in 1832, Ljudevit Gaj who received permission from the royal government of Habsburg for printing the first newspaper in the Croatian language, Josif Runjanin, who wrote the lyrics for the Croatian national anthem, Vatroslav Lisinski, composer of the first Croatian language opera, "Ljubav i zloba" ("Love and Malice", 1846), and many others.
Fearful first of Hungarian and then Habsburg pressure of assimilation, the Kingdom of Croatia had always refused to change the status of Latin as its official language until the middle of the 19th century. Only on 2 May 1843 the Croatian language was first spoken in parliament, finally gaining official status in 1847 due to the popularity of the Illyrian movement.
Even with a large Slavic (Croatian) majority, Dalmatia retained large Italian communities in the coast (in the cities and the islands, largest concentration in Istria). According to the 1816 Austro-Hungarian census, 22% of the Dalmatian population was Italian-speaking. Starting in the 19th century, most Dalmatian Italians gradually assimilated to the prevailing Croatian culture and language.
The Croatian answer to the Hungarian revolution of 1848 was declaration of war. Austrian, Croatian and Russian forces together defeated the Hungarian army in 1849 and the following 17 years were remembered in Croatia and Hungary as Germanization. The eventual failure of this policy resulted in the Austro-Hungarian Compromise of 1867 and the creation of a monarchic union between the crowns of the Austrian Empire and the Kingdom of Hungary. The treaty left unanswered the question of the status of Croatia. The following year the Croatian and Hungarian parliaments created a constitution for union of the Kingdom of Croatia-Slavonia and the Kingdom of Hungary.
After the Ottoman Empire lost military control over Bosnia and Herzegovina, Austria-Hungary abolished Croatian Krajina and Slavonian Krajina, restoring the territories to Croatia in 1881. During the second half of the 19th century pro-Hungarian political parties played Croats against Serbs with the aim of controlling the parliament. This policy failed in 1906 when a Croat-Serb coalition won the elections. The newly created political situation remained unchanged until the advent of World War I.
On 29 October 1918, the Croatian Sabor (parliament) declared independence, creating the new State of Slovenes, Croats and Serbs. Pressured by the Italian army, which was entering its territory from south and west, the National Council (Narodno vijeće) started expedient negotiations with the Kingdom of Serbia and on November 23 1918, a delegation was sent to Belgrade with the aim of a proclamation of union. The National Council delegation delivered 11 points which needed to be fulfilled for the creation of a future state. The most important of these points was the first, which referred to the need of a constitution for the new state, a proposal that was passed with a two thirds majority. Eventually, a constitution for a centralized state was passed with a majority of 50% + 1 vote and caused the end of state autonomy. On 1 December 1918, the new Kingdom of Serbs, Croats, and Slovenes, colloquially known as Kingdom of Yugoslavia, was created. This decision created public outcry among Croats, which started a political upheaval for the restoration of state autonomy by the leadership of the Croatian Peasant Party.
The unhealthy political situation in Yugoslavia became much worse after Stjepan Radić, the president of CPP, was killed in the Yugoslav parliament building in 1928 by Serbian ultra-nationalist Puniša Račić.
The ensuing chaotic period ended the next year when King Alexander abolished the Constitution, prorogued the Parliament and introduced a personal dictatorship. The next 4 years of the Yugoslav regime were described by Albert Einstein as a "horrible brutality which is being practised upon the Croatian People". During the dictatorship, Vladko Maček, leader of the Croatian Peasant Party, was imprisoned, only becoming free after king Alexander was killed in a plot organized by a Croatian right wing extremist movement, the Ustaše. Upon Maček's release, the political situation was restored to that before the murder of Stjepan Radić, continuing Croatian demands for autonomy. The Croatian question was solved only on August 26, 1939 by the Cvetković-Maček Agreement, when Croatia received autonomy and an extension of its borders and Maček became Yugoslav vice-prime minister. The ensuing peace was short lived, and only lasted until the German invasion of 1941.
The German invasion of 6 April 1941 achieved victory over the Royal Yugoslav Army in little more than ten days, ending with the unconditional surrender of the Royal Yugoslav Army on April 17. The territory of Croatia, Bosnia and Herzegovina and the region of Syrmia in Vojvodina became a puppet state of Nazi Germany called the Independent State of Croatia. Istria, the port city of Rijeka, and a portion of Dalmatia up to Split were occupied by Italy. Baranja and Medjumurje which were occupied by Hungary. Although the recently returned exiled Ustashe was in charge of the new regime, the Axis occupiers initially offered the state leadership to Vladko Maček, the leader of the Croatian Peasants' Party (HSS), but he refused. Only one day after entering Zagreb, on April 17, 1941, Ante Pavelić proclaimed that all people who offended, or tried to offend against the Croatian nation were guilty of treason — a crime punishable by death. The Ustashe regime introduced anti-Semitic Nuremberg-style laws, and also conducted massacres of mostly Serbs and other non-Croats, as well as running concentration camps such as the one at Jasenovac and Stara Gradiska where opponents of the Ustashe regime and other 'undesirables' were held. Catholic priests who were involved in the Ustashe movement, particularly the notorious Father Miroslav Filipović were defrocked. While others such as the Archbishop of Zagreb Alojzije Stepinac not only condemned Ustashe crimes in his sermons, but also offered refuge and protection to persecuted Serbs and Jews.
The remnants of the Royal Yugoslav Army, later reorganized into the predominantly Serbian Chetniks, offered resistance to the Nazi occupation and their Ustashe collaborators. Later, in response to Hitler's surprise "Operation Barbarossa" attack on the Soviet Union, a massive uprising began on June 22 1941 with the creation of 1st Sisak Partisan Detachment. The leadership of the Yugoslav partisan movement was in the hands of Croat Josip Broz Tito, whose policy of brotherhood and unity would in the end defeat not only the Axis occupiers, but also their collaborators in the armed forces of the Independent State of Croatia and their other non-Communist rivals Chetnik forces led by Serbian Royalists. The victory of Tito's partisans against the Nazi occupiers and their allies resulted in the massacres of those Croatian Domobran (Home Guard) and Ustashe who were repatriated from Austria by the British 8th Army. In the decade after World War II, up to 350,000 ethnic Italians left Yugoslavia.
The number of World War II victims in Yugoslavia remains a source of much controversy amongst Serb and Croat nationalist academics and historians on the one side, and independent researchers, mostly notably Vladimir Žerjavić (a Croat) and Bogoljub Kočović (a Serb), on the other.
Modern Croatia was founded on AVNOJ anti-fascist partisans' principles during the second world war, and it became a constitutional federal republic of the Socialist Federal Republic of Yugoslavia. A Communist dictatorship was established but, due to the Tito-Stalin split, economic and personal freedom were better than in the Eastern Bloc. From the 1950s, the Socialist Republic of Croatia enjoyed an autonomy under the rule of the local Communist elite, but in 1967 group of influential Croatian poets and linguists published a Declaration on the Status and Name of the Croatian Standard Language. After 1968 the patriotic goals of that document morphed into a generic Croatian movement for more rights for Croatia, greater civil rights and demands for the decentralization of the economy. In the end the Yugoslav leadership interpreted the Croatian Spring as a restoration of Croatian nationalism, dismissed the movement as chauvinistic and arrested most important leaders. In 1974, a new Yugoslav federal constitution was ratified that gave more autonomy to the individual republics, thereby basically fulfilling the main goals of the Croatian Spring.
The circle of nationalistic violence which destroyed Yugoslavia started with Albanian demands in 1981 for Kosovo to be removed from Serbia and become a constituent republic inside Yugoslavia. Nationalistic sentiments followed for the Yugoslav states with the Serbian SANU Memorandum in 1986 and later with Croatia and Slovenia's response in 1989 after Serbia organized coups in Vojvodina, Kosovo and Montenegro.
Under the influence of Slobodan Milošević's propaganda the importance of who won the first Croatian multi party elections in 50 years was diminished, because ,allegedly, Serbs influenced both Croatian nationalist leader Franjo Tuđman and communist leader Ivica Račan. The electoral win of Franjo Tuđman further inflamed the situation in Croatia: Serbs left the Croatian parliament and created the Association of the Municipalities of Northern Dalmatia and Lika in Knin, which was later to become the Republika Srpska Krajina. On the events of 1990-92, Milan Babić, president of Republika Srpska Krajina, was later to declare that he had been "strongly influenced and misled by Serbian propaganda". These events culminated in the full scale Croatian War of Independence in 1991 which lasted until Operation Storm (also known as the Oluja), when most of what is known as today's Croatia was established by the Croatian Army. On 6 August 1995, the leadership of the Republika Srpska Krajina gave the order that all Serbs would have to leave Croatia for Bosnia and Herzegovina .
Croatia was internationally recognized on 15 January 1992, by the European Union and the United Nations, at a moment when it didn't have full sovereignty over more than 1/3rd of its territory. The first country to recognize Croatia was Iceland on 19 December 1991.