This and other evidence prepare us for the establishment, in the tenth century, of the most characteristic of all Viking settlements, that of Jómsborg on the Island of Wollin at the mouth of the Oder. According to tradition King Gorm the Old conquered a great kingdom in Wendland, but it was to his son Harold Bluetooth that the definite foundation of Jómsborg was ascribed. For many years there had been an important trading centre at Julin on the Island of Wollin, where traders from Scandinavia, Saxony, Russia and many other lands met together to take part in the rich trade between north and south, east and west, which passed through Julin, standing as it did on one of the great waterways of central Europe. Large finds of Byzantine and Arabic coins bear witness to the extensive trade with Greece and the Orient which passed through Julin, while the Silberberg, on which Jómsborg once stood, is so called from the number of silver coins from Frisia, Lorraine, Bavaria and England which have been found there. It was no doubt in the hope of securing some fuller share in this trade that Harold established the great fortress of Jómsborg and entrusted its defence to a warrior-community on whom he imposed the strictest rules of organisation. The story of the founding of Jómsborg is told in the late and untrustworthy _Jómsvikingasaga_, but, while we must reject many of the details there set forth, it is probable that the rules of the settlement as given there are based on a genuine tradition, and they give us a vivid picture of life in a Viking warrior-community. No one under eighteen or over fifty years of age was admitted to their fellowship, and neither birth nor friendship, only personal bravery, could qualify a man for admission. No one was allowed to continue a member who uttered words of fear, or who fled before one who was his equal in arms and strength. Every member was bound to avenge a fallen companion as if he were his brother. No women were allowed within the community, and no one was to be absent for more than three days without permission. All news was to be told in the first instance to their leader and all plunder was to be shared at a common stake. The harbour of Jómsborg could shelter a fleet of 300 vessels and was protected by a mole with twelve iron gates. The Jómsvikings played an important if stormy part in the affairs of the three Scandinavian kingdoms in the later years of the 10th and the early 11th century. Many of them came to England in the train of king Svein, while Jarl Thorkell was for a time in the service of Ethelred the Unready. The decline of Jómsborg as a Viking stronghold dates from its devastation by Magnus the Good in 1043, but the importance of Julin as a trading centre continued unimpaired for many years to come.