Norse traditions were replaced slowly by Christian ones in the late 10th and early 11th centuries. One of the most important sources for the history of the 11th century Vikings is the treaty between the Icelanders and Olaf Haraldsson, king of Norway circa 1015 to 1028. This is largely attributed to the missionary kings Olav Tryggvasson and St. Olav. Haakon the Good was Norway's first Christian king, in the mid-10th century, though his attempt to introduce the religion was rejected. Born sometime in between 963 and 969, Olav Tryggvasson set off raiding in England with 390 ships. He attacked London during this raiding. Arriving back in Norway in 995, Olav landed in Moster. There he built a church which became the first Christian church ever built in Norway. From Moster, Olav sailed north to Trondheim where he was proclaimed King of Norway by the Eyrathing in 995.