Long Rider Temuujin Zemuun and Mongol Derby winner Shiravsamboo Galbadrakh.
He also said he was asked to ride in the event and received money to take part.
Others in the field were required to pay an entry fee of nearly $US5000 and raise money for charity to compete in the August relay race.
CuChullaine O'Reilly, the founder of the Long Riders' Guild, an international association of equestrian explorers, believes the Mongolian entry was aimed at offsetting criticism and the event was "an act of equestrian colonialism".
O'Reilly, in what he says will be his final comment on the race, recounted the remarkable efforts of a Mongolian horseman, Temuujin Zemuun, to track down and interview the Mongolian rider on the remote steppes.
In the interview, the rider, Shiravsamboo Galbadrakh, disputes the official race result that put him first equal with South African Charles van Wyk.
He said he had won the race outright.
British firm The Adventurists, which organised the race, initially reported on August 29 on its website: "First across the line was the Mongolian rider, followed only one minute later by the South African, Charles Van Wyk."
However, some days later The Adventurists stated: "Joint first was awarded to Charles van Wyk of South Africa and Shiravsamboo Galbadrakh of Mongolia."
Temuujin had voiced his opposition to the race in the local Mongolian press. Thereafter, he set off to ride across Mongolia. It was on his return he set about trying to find Shiravsamboo.
"Mongolia is the size of Texas, so finding one nomadic herder wasn't going to be easy," O'Reilly said in his latest missive on the race.
"Yet modern technology has made remarkable inroads. After repeated attempts, Temuujin managed to obtain the location of the camp of Shiravsamboo Galbadrakh.
"His first attempt to find the winner failed, as it transpired the man who had won Mongolia's longest horse race was a simple herder who was now tending his animals out on the trackless steppes.
"Refusing to give up, Temuujin made a second journey, this time through a snow storm. At a ger/yurt deep in the countryside, with winter pressing in, Temuujin the Long Rider met Shiravsamboo the Mongol Derby winner.
"In an on-the-record, filmed interview, Temuujin asked his fellow Mongolian equestrian to explain to the world his background, as well as his sudden appearance in the horse [race]."
Shiravsamboo, 26, who is unmarried, said in the interview that he did not speak English or any other foreign language.
"Because of this, none of the foreign contestants could speak to him or learn the nature of his involvement in the Mongol Derby," O'Reilly wrote.
Shiravsamboo was informed of the race three days before its start. He said he was recruited by representatives of the Adventurists to ride, who said it was important to the company that a Mongolian should participate.
He said he was not told that the foreign contestants had paid to participate and said he did not personally raise funds for charity through his participation.
He received 300,000 tugrugs - about $US250 - to race. (The average yearly income in Mongolia is $US2100.)
"Shiravsamboo expressed his anger to Temuujin when he learned to his dismay that the organisers of the event were broadcasting the news that he had 'shared' the victory with one of the foreign riders," O'Reilly said.
"According to Shiravsamboo, he did not tie with Charles van Wyk. He believes 100 per cent that he won the race without any assistance. He did not know that the Adventurists now claim that the foreign contestant tied with him.
"Shiravsamboo insists that he won all by himself and is adamant that he is the sole winner."
O'Reilly reported that Temuujin was unable to share his findings immediately.
He had difficulty travelling back across the snow-covered country. Once he reached the capital, he discovered that a flu epidemic had effectively shut down the city, making it impossible for him to find a translator straight away.
"It was only after overcoming all of these difficulties that the Mongolian Long Rider was able to transmit the news back to Guild HQ."
O'Reilly, a vocal critic of the race, described the event as a battleground over equestrian ethics. Before its running, he had voiced concerns over the welfare of the 800 or so horses involved in the event.
The Adventurists then released more details around the running of the race and veterinary support.
In a deal brokered through the International Equestrian Federation, additional veterinary support was offered by the government of the United Arab Emirates and accepted by the race organisers.
O'Reilly said the Adventurists declined to comment on Shiravsamboo's views when contacted by the Long Riders' Guild.
The Adventurists recently announced that the Mongol Derby would be run again, in 2010. It will now be open to 35 contestants - there were 25 in 2009 - and the entry fee has risen to $US9500.
The Mongolia Today newspaper reports on the Press Conference held by Long Riders Temuujin Zemuun, Batmonkh Muntuush and Bonnie Folkins. Pictured also is the delivery of the international petition to the President by the Long Riders and Buddhist monks.