From The Art and Popular Culture Encyclopedia
Montanism was an early Christian movement of the late 2nd century, later referred to by the name of its founder, Montanus, but originally known by its adherents as the New Prophecy. It originated in Phrygia, a province of Asia Minor, and flourished throughout the region, leading to the movement being referred to elsewhere as Cataphrygian (meaning it was "from Phrygia") or simply as "Phrygians". It spread rapidly to other regions in the Roman Empire at a time before Christianity was generally tolerated or legal. It persisted in some isolated places into the 6th century.
Although it came to be labelled a heresy, the movement held similar views about the basic tenets of Christian doctrine to those of the wider Christian Church. It was a prophetic movement that called for a reliance on the spontaneity of the Holy Spirit and a more conservative personal ethic. Parallels have been drawn between Montanism and modern day movements such as Pentecostalism, the charismatic movement, and the New Apostolic Reformation.