Vironia (mod. Virumaa, Estonia; Ger. Wierland) was a province of medieval Livonia on the southern coast of the Gulf of Finland, roughly situated between the rivers Loop, Valgejôgi, and Narva.
In 1217 German crusaders from Riga raided Vironia for the first time, but in the following years the province was subjected by the Danes from Reval, although the Germans persisted in their claims. It was only the Treaty of Stensby (1238) that definitively placed the province under the rule of the king of Denmark.
Most of the land in Vironia was enfeoffed to the vassals of the king. According to the land register known as the Liber Census Daniae, the most powerful among the new magnates was Dietrich von Kievel; some native Estonians also appear among the lesser vassals. During the Danish period, the two main urban centers of Vironia were Wesenberg (mod. Rak- vere, Estonia), at the foot of a royal castle, and the economically more important town of Narva on the eastern frontier. In 1346, along with the rest of Danish Estonia, Vironia was sold to the Teutonic Order.
Bailiwicks of the order were established in Wesenberg and Narva, and during the fifteenth century the order erected the new castles of Tolsburg on the coast and NeuschloB on the northern shore of Lake Peipus, where the river Narva exits the lake. In 1558 the Russians were able to quickly conquer most of Vironia. Along with the rest of Estonia, it came under Swedish rule in the 1580s.