The Norwegian language has evolved from a common Scandinavian language, called urnordisk, which was used in the first millennium after Christ. Preserved examples of this language have been found in some inscriptions. However in the time before the Viking Age the language itself changed and the structure became simpler, while there was a difference between the western branch, which we now call norrønt, and an eastern branch, which eventually would develop into Swedish and Danish.
We assume that the old Norwegian was in use until the last half of the 1300s. Then Norwegian became simpler and the grammar was simplified. This stage lasted until around 1500. In 1536, the union with Denmark was tied and the Catholic Church was replaced by the Lutheran state church. Danish had then long been the dominant written language, but now it became the only written language in Norway.
Danish became the only written language in Norway for many years from around 1500 to about 1850. This language was initially inconsistent and varied, but did eventually take on a firmer shape. When the Bible was published in Danish in 1550, it was very much so through the religious language that Norwegians eventually learned to read and write. A Danish-based upper-class dialect developed in the 1600s – and the 1700s.