Yule was celebrated in Scandinavia and elsewhere on a variety of calendar dates before a Roman bishop decided that the birth of Christ should be placed to December 25. This happened about the year 300.
In Jerusalem it generated protests when the Christmas Day was transferred from January 6 in the year 440. The Norwegian custom of “drinking yule” was transferred to December 25 by King Håkon “the good” around the year 900.
He had given up the attempt to bring christianity to Norway, but succeeded in moving the midwinter celebration to “the birthday of Christ”.
The Scandinavian forebears drank yule for thirteen days, from December 24 to January 6. The church moved the new years celebrations to right after Christmas, this way the feasting could have the same duration as the norse celebrations of old. This is how Christianity eased into Viking society.