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A trove of historical documents that shed fresh light on the origins of baseball sold at auction on Sunday for more than $3.2 million, a record auction price for papers related to the sport that became America's "national pastime."

The 23 pages of yellowed documents included original notes about the setting of official rules of the then-emerging sport of base ball, which evolved in the 19th century from earlier games using bats and balls.

The notes were written by Daniel Lucius "Doc" Adams, president of the New York Knickerbockers Base Ball Club, when 14 clubs convened in New York City in January 1857 to codify rules for the sport, which gradually became known by a single word, baseball.

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The documents, entitled the "Laws of Base Ball," were expected to sell for about $1 million, said SCP Auctions, the California auction house that conducted the sale. Bidding began on April 6 and extended just over two weeks online.

The winning bidder wished to remain anonymous, said Terry Melia, a SCP Auctions spokesman.

"Its gravitas was recognized by a diverse collection of astute bidders who pushed the bidding to a record level," Dan Imler, SCP vice president, said in a statement, referring to the papers.

The papers cast further doubt on the claim that Abner Doubleday, a Union general in the American Civil War, invented baseball in Cooperstown, New York, in the 1830s. The town was selected as the home of the National Baseball Hall of Fame largely on the basis of the claim, even though there is scant evidence to support it.

The 1857 documents set the distance between bases in a baseball diamond at 90 feet, established nine "innings" as the standard game length and set the minimum number of players on a team at nine. Major League Baseball still uses those rules.

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For generations, the family of William Grenelle, a New York Knickerbockers delegate to the 1857 convention, owned the documents, and they were sold in 1999 for about $12,000 with little fanfare to an anonymous bidder, said Melia.

The winning bid in the most recent auction broke the previous record for a baseball document. Babe Ruth's 1918 Boston Red Sox contract fetched $1.7 million when it was sold in 2014.