Question: What county contains the location of formation of Slipknot?

full_context: Document 1: Kirtland Records: In 2003, John Kirtland co-founded Kirtland Records with his wife, The Polyphonic Spree choir member Jenny Kirtland. Kirtland Records leveraged the Bush back catalog rights to secure a national distribution deal with RED Distribution, which remains the label's distributor. Kirtland Records went on to become the record label for a number of Texas-based indie bands, including the Burden Brothers, The Polyphonic Spree, Toadies, The Vanished, and Sarah Jaffe.
Document 2: Kanye West: West founded the record label and production company GOOD Music in 2004, in conjunction with Sony BMG, shortly after releasing his debut album, The College Dropout. John Legend, Common, and West were the label's inaugural artists. The label houses artists including West, Big Sean, Pusha T, Teyana Taylor, Yasiin Bey / Mos Def, D'banj and John Legend, and producers including Hudson Mohawke, Q-Tip, Travis Scott, No I.D., Jeff Bhasker, and S1. GOOD Music has released ten albums certified gold or higher by the Recording Industry Association of America (RIAA). In November 2015, West appointed Pusha T the new president of GOOD Music.
Document 3: Saylorville, Iowa: Saylorville is a census-designated place (CDP) in Polk County, Iowa, United States. The population was 3,301 at the 2010 census. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area. The Saydel Community School District is located in this area. The unincorporated community of Marquisville is in this area.
Document 4: Middletown, Iowa: Middletown is a city in Des Moines County, Iowa, United States. The population was 318 at the 2010 census. It is part of the Burlington, IA–IL Micropolitan Statistical Area.
Document 5: Colo, Iowa: Colo is a city in Story County, Iowa, United States. The population was 876 at the 2010 census. It is part of the Ames, Iowa Metropolitan Statistical Area, which is a part of the larger Ames-Boone, Iowa Combined Statistical Area.
Document 6: Squint Entertainment: Squint Entertainment was a record label owned by Word Entertainment, started in 1997 and run by musician and songwriter Steve Taylor. Squint pushed Sixpence None the Richer to mainstream success with their single "Kiss Me". (The band had been in the CCM genre for several years before that). Other successful bands, such as Chevelle, emerged from Squint's brief creative life.
Document 7: Fort Dodge, Iowa: Fort Dodge is a city in and the county seat of Webster County, Iowa, United States, along the Des Moines River. The population was 25,206 in the 2010 census, an increase from 25,136 in the 2000 census. Fort Dodge is a major commercial center for North Central and Northwest Iowa. It is located on U.S. Routes 20 and 169.
Document 8: Royal Empire Records: Originating in Washington State during 2001 as REK Squad Entertainment, Royal Empire Records founder Edward Galloway and co-founder Mario Lyons set out on a mission to transcend to the top of the music industry. Although the path was long and the participants in that quest have changed frequently, Edward Galloway's mission has not. In 2003, Edward Galloway & Mario Lyons' vision of a successful record label came to life as Royal Empire Records.
Document 9: Des Moines metropolitan area: The Des Moines metropolitan area, officially known as the Des Moines -- West Des Moines, IA Metropolitan Statistical Area (MSA), consists of five counties in central Iowa, United States: Polk, Dallas, Warren, Madison, and Guthrie. The 2010 census population of these counties was 569,633, and the 2017 estimated population was 645,911.
Document 10: Curb Appeal Records: Curb Appeal Records was an American record label founded in Kansas City, Missouri by The Get Up Kids guitarist and Blackpool Lights frontman Jim Suptic.
Document 11: Mike Varney: Mike Varney is an American musician, record producer, music publisher and impresario. He is the founder of the Shrapnel Label Group, which includes Shrapnel Records, Tone Center Records and Blues Bureau International. He also has a 50% stake in Magna Carta Records, a New York-based label. Amazon.com currently lists over 790 albums as being released by record labels founded or owned by Mike Varney. He is often credited with being the individual most responsible for popularizing the mid-1980s shred guitar boom, and has continuously specialized in producing highly acclaimed musicians within the genres of instrumental rock, hard rock, jazz, jazz fusion, blues, blues-rock, progressive metal and speed metal.
Document 12: Great Big Mouth Records: Great Big Mouth Records is a record label based in Des Moines, Iowa, which was founded by Slipknot and Stone Sour frontman Corey Taylor and Denny Harvey. The label was conceived to help bring attention to Midwestern bands, Taylor explains; "basically we're just trying to unify the scene and really bring more attention to the Midwest than there is right now.".
Document 13: Kalona, Iowa: Kalona is a city in Washington County, Iowa, United States. It is part of the Iowa City, Iowa Metropolitan Statistical Area. The population was 2,363 at the 2010 census. Kalona is the second largest city in Washington County.
Document 14: Indianola, Iowa: Indianola is a city in Warren County, Iowa, United States, 18 miles south of Des Moines, Iowa. The population was 14,782 at the 2010 census. It is the county seat of Warren County.
Document 15: Corydon, Iowa: Corydon is a city in Wayne County, Iowa, United States. The population was 1,585 in the 2010 census, a decline from 1,591 in the 2000 census. It is the county seat of Wayne County.
ground_truth: Warren County
sub_queries: Slipknot >> location of formation Answer: Des Moines
Des Moines >> located in the administrative territorial entity Answer: Warren County