Norwegian language
During the 13th century the Black Death killed two thirds of the population of Norway.  The Danish kings and queens noticed that Norway was weak and defenceless, so they annexed Norway (made it part of Denmark).  For hundreds of years Norway was ruled by the Danes.  All the rulers, priests, estate owners and noblemen were Danish.  Many of them settled in Norway.  This is why today’s standard Norwegian (Bokmål) is similar to Danish.  Norwegians were not allowed to print books in Norwegian.  Anyone wanting to study had to go to Denmark or Germany.