Celtic rock is a genre of folk rock. It is also a type of Celtic fusion which uses Celtic music, instrumentation and themes into rock music. It has been popular since the early 1970s. It was an important foundation for developing of very successful mainstream Celtic bands and popular musical performers. It was also important for creating other types of music genres. It is important keeping and defining regional and national identities and in fostering a pan-Celtic culture. It has also helped to introduce those cultures to other people.