The High Middle Ages was the period of European history in the 11th, 12th, and 13th centuries (AD 1000-1300). The High Middle Ages were preceded by the Early Middle Ages and followed by the Late Middle Ages, which by convention end around 1500.

The key historical trend of the High Middle Ages was the rapidly increasing population of Europe, which brought about great social and political change from the preceding era. By 1250, some scholars say, the continent became overpopulated, reaching levels it would not see again in some areas until the 19th century. This trend was checked in the Late Middle Ages by a series of calamities, notably the Black Death but also including numerous wars and economic stagnation.

From about the year 1000 onwards, Western Europe saw the last of the barbarian invasions and became more politically organized. The Vikings had settled in the British Isles, France and elsewhere, whilst Norse Christian kingdoms were developing in their Scandinavian homelands. The Magyars had ceased their expansion in the 10th century, and by the year 1000, a Christian Kingdom of Hungary was recognized in central Europe. With the brief exception of the Mongol invasions, major barbarian incursions ceased.

In the 11th century, populations north of the Alps began to settle new lands, some of which had reverted to wilderness after the end of the Roman Empire. In what is known as the "great clearances," vast forests and marshes of Europe were cleared and cultivated. At the same time settlements moved beyond the traditional boundaries of the Frankish Empire to new frontiers in eastern Europe, beyond the Elbe River, tripling the size of Germany in the process. Crusaders founded European colonies in the Levant, the majority of Spain was conquered from the Moors, and the Normans colonized southern Italy, all part of the major population increase and resettlement pattern.

The High Middle Ages produced many different forms of intellectual, spiritual and artistic works. This age saw the rise of modern nation-states in Western Europe and the ascent of the great Italian city-states. The still-powerful Roman Church called armies from across Europe to a series of Crusades against the Seljuk Turks, who occupied the Holy Land. The rediscovery of the works of Aristotle led Thomas Aquinas and other thinkers to develop the philosophy of Scholasticism. In architecture, many of the most notable Gothic cathedrals were built or completed during this era.