There is a theory that "morris" dancing was originally "moorish" dancing; that the love poetry of the troubadors was derived from the ecstatic devotional poetry of the Sufis; that the founding of such organizations as the Order of the Garter, the Knights of Malta, and the Freemasons was inspired by imitation of the various Sufi orders in the Middle East; and that all this began because of the Crusades.

See Idries Shah's book "The Sufis" for more information.