It is believed that Germanic peoples originally adopted the ethnonym from the ancient Veneti and after the migration period transferred it to their new easterly neighbours, the Slavs (see Relation between Veneti and Slavs for further details).
For the medieval Scandinavians, a Wend (Vender) was a Slav originating from the southern shore of the Baltic sea (Vendland), the term was therefore used to refer to Polabian Slavs like Obotrites, Rugian Slavs, Veleti and Pomeranian tribes.
For people living in medieval Northern Holy Roman Empire and its precursors, especially for the Saxons, a Wend (Wende) was a Slav living west of the Oder River area, an area entitled later as Germania Slavica, settled by the Polabian tribes mentioned above in the north and others, e.g. the Sorbs and the Milceni, in the south.
The Germans in the South used the term Winde instead of Wende and applied it, just as the Germans in the North, to Slavs they had contact with, e.g. Polabian people from Bavaria Slavica or the Slovenians (the names Windic march and Windisch Feistritz are still testimony to this historical denomination).
Following the 8th century, nearly all wendish land was organized in marches by the Frankish kings and their successors. By the 12th century, all wendish lands had become part of the Holy Roman Empire. In the course of the Ostsiedlung, reaching its peak in the 12th to 14th centuries, this land was settled by Germans and in all meanings reorganized. The term Wends now referred to Slavic-speaking minorities within the empire, whereas the Slavs east of the new border were not termed Wends, but Poles, Czechs etc.
Due to the process of assimilation following German settlement, many Slavs mixed with the Germans and/or adopted their culture and language. Only some rural communities that did not show strong admixture with Germans and continued to use West Slavic languages tongues were still termed Wends. With the gradual decline of the use of these local Slavic tongues, the term Wends slowly disappeared, too.
Today, only two groups of Wends still exist: the Lusatian Sorbs in present-day eastern Germany and the Pomeranian Kashubs in present-day northern Poland. Yet, today they are referred to as Sorbs and Kashubs rather than Wends.
In the third book of his Geographia, Ptolemy mentions the Ouenedai among other dwellers on the Baltic shore in the middle of the 2nd century CE. Some early scholars suggested the Ouenedai are synonymous with the Wends, however, based on linguistic facts, modern academic views now argue that the Ouenedai were ethnolinguistically different from Slavs and hence cannot be equated with Wends.
As a part of the Slavic migrations in the first millennium, splitting the just evolved Slav ethnicity into Southern, Eastern and Western groups, some West Slavs moved into the areas between the Elbe and Oder Rivers from east to west and from south to north. There, they assimilated the remaining Germanic population that had not left the area in the Migration period. Their German neighbors adapted the term they had been using for peoples east of the Elbe River before to the Slavs, calling them Wends as they called the Venedi before and probably the Vandals also.
While the Wends were arriving in so-called Germania Slavica as large homogeneous groups, they soon divided into a variety of small tribes, with large strips of woodland separating one tribal settlement area from another. Their tribal names were derived from local place names, sometimes adopting the Germanic tradition (e.g. Heveller from Havel, Rujanes from Rugians). Settlements were secured by round burghs made of wood and clay, where either people could retreat in case of a raid from the neighboring tribe or used as military strongholds or outposts.
Some tribes unified to larger, duchy-like units. E.g., the Obotrites evolved from the unification of the Holstein and Western Mecklenburg tribes led by mighty dukes known for their raids into German Saxony. The Pomeranians, the only Wends east of the Oder River (in contrast, the Poles south of the Warthe River are not called Wends), emerged from the tribes north of the Warthe River and around the mouth of the Oder River, and were led by a duke, too. The Liutizians were an alliance of tribes living between Obotrites and Pomeranians. They did not unify under a duke, but remained independent and had their leaders meet and decide in the temple of Rethra.
In 983, many Wend tribes participated in a great uprising against the Holy Roman Empire, which before had established Christian missions, German colonies and German administrative institutions (Marken such as Nordmark and Billungermark) in pagan Wendish territories. The uprising was successful and the Wends delayed Germanisation for about two centuries.
After that victory, Wends were under increasing pressure from Germans, Danes and Poles. The Polish invaded Pomerania several times. The Danish often raided the Baltic shores (and, in turn, were often raided by the Wends). The Holy Roman Empire and its margraves tried to restore their marches.
In 1068/69, a German expedition took and destroyed Rethra, one of the major pagan Wend temples. The Wendish religious centre shifted to Arkona thereafter. In 1124 and 1128, the Pomeranians and some Liutizians were baptised. In 1147, the Wend crusade took place.
In 1168 during the Northern Crusades, Denmark mounted a crusade lead by Bishop Absalon and King Valdemar the Great against the Wends of Rugia in order to convert them to Christianity. They captured and destroyed Arkona, the Wendish temple fortress, and tore down the statue of the Wendish god, Svantevit. With the capitulation of the Rugian Wends, the last independent pagan Wendish were defeated by the surrounding Christian feudal powers.
From 12th to 14th century, German colonists were called in the Wend lands and settled there in large numbers, changing the area from Slav to German. The settlers were called in by local dukes and monasteries to repopulate land devastated in the wars, to cultivate the large woodlands and heavy soils that have not been settled before, and to found cities as part of the "Ostsiedlung" (German eastward expansion).
The German population assimilated most of the Wends, making them disappear as an ethnic minority except for parts of the Kashubs and Sorbs. The Polabian language survived until the beginning of the 19th century in what is now the German state of Lower Saxony. Yet, many place names and some family names in eastern Germany still are of Wendish origin today. Also, the Dukes of Mecklenburg, of Rügen and of Pomerania had Wendish ancestors.
Between 1540 and 1973, the kings of Sweden were officially called king of the Swedes, the Geats and the Wends (in Latin translation king of Suiones, Goths and Vandals) (Sw. Svears, Götes och Wendes Konung). The current monarch, Carl XVI Gustaf would be able to use the same title, but chose his royal title to be simply King of Sweden (Sveriges Konung), thereby changing an age-old tradition.
The term Wends was also used in history in the following meanings: