The Istari were said to come to Middle-earth in the Second Age (the Blue Wizards) and the Third Age (Saruman, Gandalf and Radagast). So I'm wondering why didn't Saruman, Gandalf or Radagast help the Dunedain in their war against Angmar; seems the wizards could have made a huge difference and even save the Dunedain kingdoms from destruction.
So why didn't they help or participate?