The Society for Creative Anachronism (SCA) is an international living history group with the aim of studying and recreating mainly Medieval European cultures and their histories before the 17th century. A quip often used within the SCA describes it as a group devoted to the Middle Ages "as they ought to have been", choosing to "selectively recreate the culture, choosing elements of the culture that interest and attract us". Founded in 1966, the non-profit educational corporation has over 20,000 paid members as of 2020 with about 60,000 total participants in the society, including members and non-member participants. The SCA's roots can be traced to a backyard party of a UC Berkeley medieval studies graduate, the author Diana Paxson, in Berkeley, California, on May Day in 1966. The party began with a "Grand Tournament" in which the participants wore helmets, fencing masks, and usually some semblance of a costume, and sparred with each other using weapons such as plywood swords, padded maces, and fencing foils. It ended with a parade down Telegraph Avenue with everyone singing "Greensleeves". The SCA still measures dates within the society from the date of that party, calling the system Anno Societatis (Latin for "in the Year of the Society"). For example, 2009 May 1 to 2010 April 30 was A.S. XLIV (44). The name Berkeley Society for Creative Anachronism was coined by science fiction author Marion Zimmer Bradley, an early participant, when the nascent group needed an official name in order to reserve a park for a tournament. "Berkeley" was dropped as the group expanded. Three other co-founders were science fiction author Poul Anderson, his wife, writer Karen Kruse Anderson, and their daughter, Astrid. In 1968, Bradley moved to Staten Island, New York and founded the Kingdom of the East, holding a tournament that summer to determine the first Eastern King of the SCA. That September, a tournament was held at the 26th World Science Fiction Convention, which was in Berkeley that year.