9th century

The 9th century was a period from 801 (represented by the Roman numerals DCCCI) through 900 (CM) in accordance with the Julian calendar.
The Carolingian Renaissance and the Viking raids occurred within this period. In the Middle East, the House of Wisdom was founded in Abbasid Baghdad, attracting many scholars to the city. The field of algebra was founded by the Muslim polymath al-Khwarizmi. The most famous Islamic scholar Ahmad ibn Hanbal was tortured and imprisoned by Abbasid official Ahmad ibn Abi Du'ad during the reign of Abbasid caliph al-Mu'tasim and caliph al-Wathiq. In Southeast Asia, the height of the Mataram Kingdom happened in this century, while Burma would see the establishment of the major kingdom of Pagan. Tang China started the century with the effective rule under Emperor Xianzong and ended the century with the Huang Chao rebellions. In America, the Maya experienced widespread political collapse in the central Maya region, resulting in internecine warfare, the abandonment of cities, and a northward shift of population.
Around the 9th century, the Igbo people of what is now southern Nigeria developed bronze casts of humans, animals, and legendary creatures. These bronzes, which were used as vessels, amulets, pendants, and sacrificial tools, are among the earliest made bronzes ever found in Nigeria. Most items were part of a burial of a nobleman culture in the northern part of the Igboland.
The Ghana (Wagadu) Empire (before c. 830 until c. 1235) was located in what is now southeastern Mauritania and western Mali. It is considered the first of the Sahelian Kingdoms, which would exist in some form until the early 20th century.
Britain experienced a great influx of Viking peoples in the 9th century as the Viking Age continued from the previous century. The kingdoms of the Heptarchy were gradually conquered by the Danes, who set up Anglo-Saxon puppet rulers in each kingdom. This invasion was achieved by a huge military force known as the Great Heathen Army, which was supposedly led by Ivar the Boneless, Halfdan Ragnarsson, and Guthrum. This Danish army first arrived in Britain in 865 in East Anglia. After conquering that kingdom, the army proceeded to capture the city of York (Jorvik) and establish the kingdom of Jorvik. The Danes went on to subjugate the kingdom of Northumbria and to take all but the western portion of Mercia. The remaining kingdom of Wessex was the only kingdom of the Heptarchy left. Alfred the Great managed to maintain his kingdom of Wessex and push back the Viking incursions, relieving the neighbouring kingdoms from the threat of the Danes following his famous victory over them at the Battle of Ethandun in 878. Alfred re-established Anglo-Saxon rule over the western half of Mercia, and the Danelaw was established which separated Mercia into halves, the eastern half remaining under the control of the Danes.
Ireland was also affected by the Viking expansion across the North Sea. Extensive raids were carried out all along the coast and eventually, permanent settlements were established, such as that of Dublin in 841. Particular targets for these raids were the monasteries on the western coast of Ireland, as they provided a rich source for loot. On such raids the Vikings set up impermanent camps, which were called longphorts by the Irish—this period of Viking raids on the coasts of Ireland has been named the longphort phase after these types of settlements. Ireland in the 9th century was organised into an amalgam of small kingdoms, called tuatha. These kingdoms were sometimes grouped together and ruled by a single, provincial ruler. If such a ruler could establish and maintain authority over a portion of these tuatha, he was sometimes granted the title of High King.
Scotland also experienced significant Viking incursions during the 9th century. The Vikings established themselves in coastal regions, usually in northern Scotland, and in the northern islands such as Orkney and Shetland. The Viking invasion and settlement in Scotland provided a contributing factor in the collapse of the kingdoms of the Picts, who inhabited most of Scotland at the time. Not only were the Pictish realms either destroyed or severely weakened, the Viking invasion and settlements may have been the reason for the movement of Kenneth MacAlpin, the king of Dál Riata at that time. The kingdom of Dál Riata was located on the western coast of Scotland, and Viking incursions destroyed it after the death of its previous king, Áed mac Boanta in 839, according to the Annals of Ulster. This may have caused the new king, MacAlpin, to move to the east, and conquer the remnants of the Pictish realms. MacAlpin became king of the Picts in 843 and later kings would be titled as the King of Alba or King of Scots.
Art in the 9th century was primarily dedicated to the Gospel and employed as basic tools of liturgy of the Roman Orthodox Church. Thousands of golden art objects were made: Sacred cups, vessels, reliquaries, crucifixes, rosaries, altarpieces, and statues of the Virgin and Child or Saints all kept the flame of western art from dying out. Architecture began to revive to some extent in the West by the 9th century, taking the form of Church facilities of all kinds, and the first castle fortifications since Roman times began to take form in simple "moat and bailey" castles, or simple "strong point" tower structures, with little refinement.