Norse mythology is the term applied to the mythology of Scandinavia in the pre-Christian period when Old Norse was the common language. The primary sources for the mythology, as we know it now, were thirteenth-century Old Norse manuscripts in Iceland. Earlier origins obviously existed, but they are unknown, as the Old Norse people, like the Celts, passed down their myths orally rather than in writing. The thirteenth-century texts were “corrupted” by the fact that their writers were Christian rather than believers in the old “pagan” religion. Christianity was slow to achieve hegemony in Scandinavia, however, so the writers of the mythology were relatively close in time to the traditions of which they wrote. It was only in the year 1000 that the Icelandic Assembly voted to replace the old religion with Christianity. The eleventh-century German historian Adam of Bremen reported sacrifices to the Norse god Odin at the great Temple in Uppsala as late as 1070.