The history of Poland spans over a thousand years, from medieval tribes, Christianization and monarchy; through Poland's Golden Age, expansionism and becoming one of the largest European powers; to its collapse and partitions, two world wars, communism, and the restoration of democracy.

The roots of Polish history can be traced to ancient times, when the territory of present-day Poland was inhabited by diverse ethnic groups, including Celts, Scythians, Sarmatians, Slavs, Balts and Germanic peoples. However, it was the West Slavic Lechites, the closest ancestors of ethnic Poles, who established permanent settlements during the Early Middle Ages. The Lechitic Western Polans, a tribe whose name denotes "people living in open fields", dominated the region and gave Poland—which lies in the North-Central European Plain—its name. The first ruling dynasty, the Piasts, emerged in the 10th century AD. Duke Mieszko I, regarded as the creator of Polish statehood, adopted Western Christianity in 966 AD. Mieszko's dominion was formally reconstituted as a medieval kingdom in 1025 by his son Bolesław I the Brave, known for his military expansions. The most successful and the last Piast monarch, Casimir III the Great, presided over a period of economic prosperity and territorial aggrandizement before his death in 1370 without male heirs.

The period of the Jagiellonian dynasty in the 14th–16th centuries brought close ties with the Lithuania, a cultural Renaissance in Poland and continued territorial expansion as well as Polonization that culminated in the establishment of the Polish–Lithuanian Commonwealth in 1569, one of Europe's great powers. The Commonwealth was able to sustain centuries-long prosperity, while its political system matured as a unique noble democracy with an elective monarchy. From the mid-17th century, however, the huge state entered a period of decline caused by devastating wars and the deterioration of its political system. Significant internal reforms were introduced in the late 18th century, such as Europe's first Constitution of 3 May 1791. The existence of the Commonwealth ended in 1795 after a series of invasions and partitions carried out by the Russian Empire, the Kingdom of Prussia and the Habsburg monarchy. From 1795 until 1918, no truly independent Polish state existed, although strong resistance movements operated. The opportunity to regain sovereignty only materialized after World War I, when the three partitioning powers were fatally weakened in the wake of war and revolution.

The Second Polish Republic was established in 1918 and existed as an independent state until 1939, when Nazi Germany and the Soviet Union invaded Poland, marking the beginning of World War II. Millions of Polish citizens of different faiths or identities perished under Nazi occupation between 1939 and 1945 through planned genocide and extermination. A Polish government-in-exile functioned throughout the war, and the Poles contributed to the Allied victory through participation in military campaigns on both the eastern and western fronts. The westward advances of the Soviet Red Army in 1944 and 1945 compelled Nazi Germany's forces to retreat from Poland, which led to the establishment of a satellite communist country, known from 1952 as the Polish People's Republic. The territorial adjustments mandated by the Allies at the end of World War II in 1945 shifted Poland's geographic centre of gravity towards the west, and the re-defined Polish lands largely lost their historic multi-ethnic character. By the late 1980s, the Polish reform movement Solidarity contributed to a peaceful transition from a planned communist economy to capitalism and a liberal parliamentary democracy. This process resulted in the creation of the modern Polish state, the Third Polish Republic, founded in 1989.

Prehistory and protohistory

In prehistoric and protohistoric times, over a period of approximately 500,000 years, the area of present-day Poland was intermittently inhabited by members of the genus Homo.. The earliest evidence of Homo erectus activity in the form of microlith artifacts was discovered at Trzebnica, in Lower Silesia.. It remains the oldest archeological site in the country, dating back to the Lower Paleolithic period of the Stone Age. The southern regions of Poland were subsequently penetrated by sporadic groups of Neanderthals. Their presence was confirmed by the stone tools unearthed in caves of the Kraków-Częstochowa Upland, a limestone formation with hills, cliffs and valleys that came to be known as the Polish Jura.

The arrival of Homo sapiens and anatomically modern humans coincided with the climatic discontinuity at the end of the Last Glacial Period (Weichselian glaciation) around 10,000 BC, when Poland became warmer and habitable.. It allowed various groups of early humans to pass the Sudeten Mountains through the Moravian Gate and the Kłodzko Valley into Lower Silesia.. The Neolithic period ushered in the Linear Pottery culture, whose founders belonged to the Danubian culture and migrated from the Danube River area beginning about 5500 BC. This culture was distinguished by the establishment of the first settled agricultural communities in modern Polish territory. Later, between about 4400 and 2000 BC, the native post-Mesolithic populations would also adopt and further develop the agricultural way of life..

Excavations indicated broad-ranging development in the New Stone Age. Most notably, the oldest samples of European cheese (5500 BC) were found in the region of Kuyavia, and a pot from Bronocice is incised with what is now believed to be the earliest-known portrayal of a wheeled vehicle (3400 BC). Toolmaking became more advanced and material was primarily sourced from quarries and mines in the Świętokrzyskie (Holy Cross) Mountains.. Artifacts that originated in this mountain region were excavated as far as Moravia and near the Baltic Sea. It is estimated that the UNESCO-protected neolithic flint mines at Krzemionki, one of Europe's largest, were utilised by the Funnelbeaker and Globular Amphora cultures from 3900 BC to 1600 BC. The only surviving example of ancient parietal art in Poland is at a flint shaft in Krzemionki and features a linear charcoal pictogram of a female figure or deity that has been since associated with fertility.

Poland's Early Bronze Age began around 2400–2300 BC, whereas its Iron Age commenced c. 750–700 BC. One of the many cultures that have been uncovered, the Lusatian culture, spanned the Bronze and Iron Ages and left notable settlement sites.. Around 400 BC, Poland was settled by Celts of the La Tène culture. They were soon followed by emerging cultures with a strong Germanic component, influenced first by the Celts and then by the Roman Empire. The Germanic peoples migrated out of the area by about 500 AD during the great Migration Period of the European Dark Ages. Wooded regions to the north and east were settled by Balts..

According to some archaeological research, Slavs have resided in modern Polish territories for only 1,500 years.. However, recent genetic studies determined that the inhabitants of Poland are also the descendants of people from before the Migration Period.. According to other archaeological and linguistic research, early Slavic peoples were likely present in parts of Poland much earlier, and may have been associated with the ancient Przeworsk culture of the 3rd century BC, though some Slavic groups may have arrived from the east in later periods.Trubačev, O. N. 1985. Linguistics and Ethnogenesis of the Slavs: The Ancient Slavs as Evidenced by Etymology and Onomastics. Journal of Indo-European Studies (JIES) , 13: 203–256. The West Slavic and Lechitic peoples as well as any remaining minority clans were organized into tribal units (Polish tribes), as outlined by the anonymous Bavarian Geographer in the 9th century.. Largely divided, it was the Western Polans in the Greater Poland region who began a process of unification and created a lasting political structure in the 10th century that subsequently became the state of Poland.

Piast period (10th century–1385)

Mieszko I

Poland was established as a state under the Piast dynasty, which ruled the country between the 10th and 14th centuries. Historical records referring to the Polish state begin with the rule of Duke Mieszko I, whose reign commenced sometime before 963 and continued until his death in 992. Mieszko converted to Christianity in 966, following his marriage to Princess Doubravka of Bohemia, a fervent Christian. The event is known as the "baptism of Poland", and its date is often used to mark a symbolic beginning of Polish statehood.. Mieszko completed a unification of the Lechitic tribal lands that was fundamental to the new country's existence. Following its emergence, Poland was led by a series of rulers who converted the population to Christianity, created a strong kingdom and fostered a distinctive Polish culture that was integrated into the broader European culture..

Bolesław I the Brave

Mieszko's son, Duke Bolesław I the Brave (r. 992–1025), established a Polish Church structure, pursued territorial conquests and was officially crowned the first king of Poland in 1025, near the end of his life. Bolesław also sought to spread Christianity to parts of eastern Europe that remained pagan, but suffered a setback when his greatest missionary, Adalbert of Prague, was killed in Prussia in 997. During the Congress of Gniezno in the year 1000, Holy Roman Emperor Otto III recognized the Archbishopric of Gniezno, an institution crucial for the continuing existence of the sovereign Polish state. During the reign of Otto's successor, Holy Roman Emperor Henry II, Bolesław fought prolonged wars with the Kingdom of Germany between 1002 and 1018..

Piast monarchy under Casimir I, Bolesław II and Bolesław III

Bolesław I's expansive rule overstretched the resources of the early Polish state, and it was followed by a collapse of the monarchy. Recovery took place under Casimir I the Restorer (r. 1039–1058). Casimir's son Bolesław II the Generous (r. 1058–1079) became involved in a conflict with Bishop Stanislaus of Szczepanów that ultimately caused his downfall. Bolesław had the bishop murdered in 1079 after being excommunicated by the Polish church on charges of adultery. This act sparked a revolt of Polish nobles that led to Bolesław's deposition and expulsion from the country. Around 1116, Gallus Anonymus wrote a seminal chronicle, the Gesta principum Polonorum, intended as a glorification of his patron Bolesław III Wrymouth (r. 1107–1138), a ruler who revived the tradition of military prowess of Bolesław I's time. Gallus' work remains a paramount written source for the early history of Poland..

Fragmentation