This is near impossible to answer because of how the samis where treated by the medieval realms they lived in. In Sweden and in Novgorod samis were treated as a lesser people that was good for nothing more than fur trade. Sweden and Novgorod had a lot of interest in having the right to tax the saami and thus more clear borders appeared in Sapmi.

The swedish and novgorodian and also Norwegians tried their best to convert the saamis and 'kill' their culture. The saami religion was outlawed and the drums that was a as important for their religion as the Bible to Christianity was banned. Owning one of the religious drums was extremely prohibited and may result in execution. Since the saami was pagans no christian law applied to them.

This conversation policy made it hard to know how the saami language was in a certain period. We only have the pieces that survived many hundreds of years of oppression.