Question: What mixed martial arts promotion that was purchased by the Ultimate Fighting Championship in 2001 used to feature Nate Diaz as a competitor?

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Nathan Donald "Nate" Diaz (born April 16, 1985) is an American professional mixed martial artist currently competing for the Ultimate Fighting Championship (UFC).  He was the winner of "The Ultimate Fighter 5".  Diaz is the younger brother of former Strikeforce Welterweight Champion and WEC Welterweight Champion, Nick Diaz.  Prior to signing with the UFC, Diaz competed in World Extreme Cagefighting, Strikeforce, and Pancrase.  As of June 6th 2017, Diaz is #8 in official UFC lightweight rankings. Fighting Network Rings, trademarked as RINGS, is a Japanese combat sport promotion that has lived three distinct periods: puroresu promotion from its inauguration to 1995, mixed martial arts promotion from 1995 to its 2002 disestablishment, and the revived mixed martial arts promotion from 2008 onward. World Series of Fighting (Canada) formerly Aggression Fighting Championship, Aggression MMA and Armageddon Fighting Championship is a Canadian Mixed Martial Arts promotion based out of Edmonton, Alberta, Canada.  The promotions made their debuts in 2009.  Armageddon Fighting Championship and Aggression MMA merged in 2012 to create Aggression Fighting Championship.  In September 2013, World Series of Fighting purchased the Aggression Fighting Championship organization to enter the Canadian market, but it was later found out the AFC executives closed down the company to join a new organization WSOF Canada. The Art of War Fighting Championship (英雄榜/Art of War/AOW) is a Chinese professional mixed martial arts promotion based in Beijing, China.  The Chinese title "英雄榜" literally translated means "Gathering of Heroes."  Art of War FC has no relation to the defunct US MMA promotion Art of War Undisputed Arena Fighting Championship.  Art of War I was held at the Beijing Sports University on November 6, 2005.  The inaugural event made it the first professional mixed martial arts contest in the People's Republic of China.  To date, AOW has held 15 events in mainland China.  Its largest event was Art of War 12 - Invincible, held at the National Olympic Sports Center Auditorium in Beijing on May 23, 2009 to an audience of around 6,000 fans.  The event attracted many international guests, including former UFC Heavyweight Champion Tim Sylvia, renowned ring announcer Michael Buffer, and experienced referee "Big" John McCarthy. Miesha Theresa Tate ( ; born August 18, 1986) is an American Mixed Martial Arts Pundit and former mixed martial artist who competed in the Ultimate Fighting Championship (UFC) and is a former UFC Women's Bantamweight Champion.  Primarily known for her grappling ability, Tate became a wrestler while attending Franklin Pierce High School in Tacoma, Washington and won a state championship during her senior year in 2005.  She began her professional mixed martial arts (MMA) career in 2007, and won the bantamweight championship of the Freestyle Cage Fighting promotion in 2009.  Tate gained increased recognition in 2011, when she won the Strikeforce Women's Bantamweight Championship.  She has also won a silver medal in the FILA Grappling Championships. The UFC Hall of Fame is a hall of fame which honors mixed martial artist and personalities, established and maintained by the U.S.-based mixed martial arts promotion Ultimate Fighting Championship.  They recognize accomplishments from Pride Fighting Championships, World Extreme Cagefighting and Strikeforce. Sean Keith Sherk (born August 5, 1973) is a retired American mixed martial artist and former UFC Lightweight Champion.  Sherk competed in the Ultimate Fighting Championship and was one of the first combatants to have been a championship competitor in multiple weight divisions (having also competed for the UFC Welterweight Championship).  He was the second UFC Lightweight Champion in the organization's history after Jens Pulver vacated his title 5 years earlier.  Sherk also spent time competing in the Japan-based organizations, PRIDE Fighting Championships and Pancrase; going undefeated in both promotions.  He holds one of the longest undefeated streaks in mixed martial arts history, with only four career losses, all to fellow-UFC Champions.  Sherk announced his official retirement from mixed martial arts competition in September 2013 having last fought three years prior. Nicholas Robert "Nick" Diaz (born August 2, 1983) is an American professional mixed martial artist who is currently signed with the Ultimate Fighting Championship (UFC).  Since beginning his career in 2001, Diaz has competed in UFC, PRIDE, Strikeforce, EliteXC, World Extreme Cagefighting (WEC), DREAM, and Shooto.  He is a former welterweight champion in Strikeforce and WEC, and is the older brother of Nate Diaz. World Extreme Cagefighting (WEC) was an American mixed martial arts (MMA) promotion founded in 2001.  It was purchased by Zuffa, LLC, the parent company of the Ultimate Fighting Championship (UFC), in 2006.  In its final incarnation, it was made up of 3 weight classes: 135 lb , 145 lb and 155 lb .  To accommodate the smaller fighters, WEC's cage was 25 feet in diameter—5 feet smaller than the standard UFC cage. The year 2005 is the 13th year in the history of the Ultimate Fighting Championship (UFC), a mixed martial arts promotion based in the United States.  In 2005 the UFC held 10 events beginning with, "UFC 51: Super Saturday".  The reality TV series The Ultimate Fighter and the UFC Ultimate Fight Night both premiered on Spike TV.  The Ultimate Fighter 1 Finale was the first ever live UFC broadcast on non-pay-per-view television.

Supporting sentences:
 Prior to signing with the UFC, Diaz competed in World Extreme Cagefighting, Strikeforce, and Pancrase. World Extreme Cagefighting (WEC) was an American mixed martial arts (MMA) promotion founded in 2001.  It was purchased by Zuffa, LLC, the parent company of the Ultimate Fighting Championship (UFC), in 2006.