Another site that was phenomenal for researching these statues in their respective museums was the Web Gallery of European Art.
A brief and incomplete sampling of these Statues would tell you they were first first carved in the late 1200's and early 1300's as Portable Religious figures...in Southern Germany, Italy, and Portugal before they found footing throughout Europe. They were often carved from well seasoned Limewood, also called Bass wood. Then they were painted with chalk - a gesso, to provide a smooth base layer for the paint (natural dyes) and gold and silver leaf. If you have not read A Perfect Red by Amy Butler, you really should. But I digress, many of the statues went from the Arabic style of a beautiful angelic carving to a more European use of fear (take a gander at Tanya's dissertation)...that is to make mankind humble of, and be afraid of God and Hell. I know this is a blunt take and there is much more, but I'll leave it here when the Protestant schism began and these statues were burned by the wagon load.