Question: Prince Among Slaves and Land of Silence and Darkness are classified as what type of film?
Context: This list of ancient Roman collegia (Latin singular collegium, meaning "joined together"; English for "college") denotes a subset of professional, religious, and burial associations that existed during the Roman Republic and Roman Empire.  The other major legal form of Roman associations were political clubs, known as "sodalitates".  The collegia played a critical sociological role in organizing Roman society, particularly among slaves and the other lower classes.  Concurrently, much of the history of collegia were left unrecorded by Roman historians, as the aristocratic authors of the time were predominantly uninterested in chronicling the labor union activities, cult worshiping rituals, and general social practices of the working classes.  Exceptions to this rule existed, such as the notable and prestigious Collegium Pistorum, the college of bakers, which received wealth, political status in the Roman Senate, and some historical attention in ancient Rome.  The most powerful of these professional collegia often had considerable political influence, including over legislation and magistrate appointments.  This professional class of collegia were modeled in the same manner as a public corporation.  However, under Roman law, collegia never were granted the same legal rights of personhood as modern corporations. Dr. Sulayman S. Nyang is professor and former chairman of the African Studies Department at Howard University in Washington, D.C.  He was a co-principal investigator of the Project MAPS and also a former deputy ambassador and head of chancery of the Gambia Embassy in Jeddah, Saudi Arabia.  Nyang has served as consultant to several national and international agencies and on the boards of the African Studies Association, the American Council for the Study of Islamic Societies, America's Islamic Heritage Museum, and the Association of Muslim Social Scientists.  He has written extensively on Islamic, African and Middle Eastern affairs.  He holds a master's degree in public administration and a Ph.D. in government from the University of Virginia.  Nyang was an advising scholar for the award-winning, PBS-broadcast documentaries "" (2002) and "Prince Among Slaves" (2007), produced by Unity Productions Foundation. Politics of the Business is the third album by American hip hop producer Prince Paul.  This album is considered to be a concept album similar to "A Prince Among Thieves".  The concept for this album, however, is the concept of following-up a concept album that did not sell too well (that album being "A Prince Among Thieves").  The album features guest appearances from Ice-T, DJ Jazzy Jeff, MF Doom, Biz Markie, Chuck D, Dave Chappelle, Chris Rock, and more. Invisible Churches among slaves in the United States were informal Christian groups where slaves listened to preachers that they chose without their master's knowledge.  The Invisible Churches taught a different message from white controlled churches and did not emphasize obedience.  Some slaves could not contact Invisible Churches and others did not agree with the Invisible Church message but many slaves were comforted by the Invisible Churches. "Roll, Jordan, Roll" (Roud 6697), also "Roll, Jordan", is a spiritual written by Charles Wesley in the 18th century which became well-known among slaves in the United States during the 19th century.  Appropriated as a coded message for escape, by the end of the American Civil War it had become known through much of the eastern United States.  In the 20th century it helped inspire blues, and it remains a staple in gospel music. In psychiatry, dysaesthesia aethiopica was an alleged mental illness described by American physician Samuel A. Cartwright in 1851, which proposed a theory for the cause of laziness among slaves.  Today, dysaesthesia aethiopica is considered an example of pseudoscience, and part of the edifice of scientific racism. Land of Silence and Darkness (German: Land des Schweigens und der Dunkelheit ) is a 1971 documentary film about deaf-blind people and their experience of life.  The film was written, directed, and produced by Werner Herzog.  Rolf Illig provided narration. Prince Among Slaves is a 2006 historical documentary directed, written and produced by Andrea Kalin and narrated by Mos Def made for PBS by Unity Productions Foundation.  The film, made in association with Spark Media and Duke Media, retells the story of Abdulrahman Ibrahim Ibn Sori, a prince from West Africa who was made a slave in the United States and freed 40 years later. A Prince Among Thieves is the second studio album by hip hop artist Prince Paul.  "A Prince Among Thieves" was well received by music critics.  Music essayist Robert Christgau has called it "the closest thing to a true rock opera you've ever heard". Alexander Milton Ross, (December 13, 1832 – October 27, 1897), was born in Belleville, Upper Canada and died in Detroit, Michigan.  Ross was an agent for the secret Underground Railroad slave escape network, known in that organization and among slaves as "The Birdman" for his preferred cover story as an ornithologist.
Answer: Land of Silence and Darkness (German: Land des Schweigens und der Dunkelheit ) is a 1971 documentary film