At first, Klans during the Reconstruction period did not burn crosses. The idea was introduced by Thomas Dixon Jr. in his novel, "The Clansmen". He took it from an old Scottish custom known as the "Crann Tara," used to declare war. It also called all clan members to defend a certain area. Most of the KKK's rituals were Scottish in origin; the group saw Medieval Europe as morally pure and white. Ten years after Dixon's book, D.W. Griffith directed The Birth of a Nation, the movie version of Dixon's novel.