The big-budget American series "Marco Polo," on the 13th-century Venetian explorer and his years at the court of the Mongol emperor Kublai Khan, is riddled with historical errors, say Mongolian viewers and experts.

Netflix has spent tens of millions of dollars on the show, touted as its answer to HBO's huge hit Game of Thrones. With swashbuckling sword fights, mass battles, intricate costumes and palace plots, the series portrays conflicts and rebellions in the Mongol empire under Kublai Khan, as seen through Marco Polo's eyes.

Kublai, the grandson of the great Mongol conqueror Genghis Khan, was a phenomenal warrior himself, reigning from 1260 to 1294, subjugating swathes of China and establishing the Yuan dynasty of Chinese emperors.

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Mongolian viewers were excited to see one of their own being cast as Kublai's brother Ariq Boke and hearing the occasional Mongol phrase, despite most leading roles going to Chinese actors or those of Chinese descent, such as Briton Benedict Wong, who plays Kublai.

But according to Mongolian historians, much of the plot plays fast and loose with the facts.

Batsukh Otgonsereenen, who spent 10 years researching his book The History of Kublai Khan, told AFP: "From a historical standpoint 20 percent of the film was actual history and 80 percent fiction."

The fate of Ariq Boke, who briefly took power following the death of their father but lost the subsequent civil war, was particularly twisted, he said.

"The part where Kublai and Ariq Boke fight to a bloody death in front of their soldiers is completely untrue," he said. "Yes, Ariq did try to seize the throne, but in history Kublai and Ariq resolve their issues."

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A concubine-assassin supposedly sent by a minister of the rival Song dynasty to seduce Kublai and kill his queen was another fantasy.

"Mongolian Khans never wed or had concubines that were totally unknown," said Otgonsereenen. "Kublai also did not live in a palace. He lived in his royal ger in Beijing, in a traditional Mongolian manner."

In a press release, Netflix described the series -- shot in Kazakhstan, Malaysia and Italy, rather than Mongolia or China -- as set in a world "replete with exotic martial arts, political skullduggery, spectacular battles and sexual intrigue."

But Otgonsereenen said the creators' research on Kublai seemed "very sloppy."

"I think they tried to show Mongolian history like Game of Thrones with conspiracy, betrayal, blood and sex," he said. "Mongolian youth who watch this series might get the wrong impression of Kublai Khan being quite cruel and perverted."

- Big in the Middle Ages -

Polo -- played by Italy's Lorenzo Richelmy in the show -- was a Venetian merchant who spent more than two decades in central Asia and China with his father and uncle, serving for years as Kublai's minister and envoy.

After his return the story of his journeys, "Book of the Marvels of the World," also known as The Travels of Marco Polo, propelled him to medieval superstardom.

Marco Polo, the legendary explorer famous for his epic journey into Asia. Corbis

He was not the first European to travel to Asia but became by far the most famous, and his descriptions of the Far East are said to have inspired Christopher Columbus to attempt to travel there himself, only to discover the Americas instead.

But U.S. critics panned the show, with news site's reviewer writing: "This is a show about Kublai Khan that doesn't realize it's about Kublai Khan because Marco Polo has better name recognition.

"Is it worth watching?" he asked rhetorically. "Eh, not really, no."

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The series, released last month, has a 30 percent rating on review aggregator, which describes it as "an all-round disappointment."

Nonetheless a second season has been commissioned.

- Neighborly tensions -

Some Mongolian viewers praise the series, and many welcome the space it gives their remote country on the global small screen.

Orgil Narangerel, who played Genghis Khan in a BBC documentary, said it was more accurate than any previous foreign portrayal of Mongolian culture.

"As a Mongol and an artist, 'Marco Polo' makes me feel like our dreams are coming true," he told AFP. "I watched all 10 episodes in just in one day."

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Although Mongol forces conquered China and ruled it for almost a century, modern Mongolia is overshadowed by its giant southern neighbor -- a key market for its raw materials -- and fears being economically dominated by it.

China proclaims itself as the world's oldest civilization and has a historical tendency to co-opt successful invaders and declare them Chinese, including Kublai.

Mongolia was later part of Qing dynasty China, only securing independence in the early 20th century and falling into the Soviet sphere soon after, while the Nationalist Republic of China maintained a sovereignty claim over the country.

Amateur film maker Narantsogt Baatarkhuu said Marco Polo correctly showed China and Mongolia as "totally different countries with different cultures and ways of life."

Movie blogger Tegshjargal Jalanajav added: "To people who like to argue that Kublai Khan was a Chinese king, this show makes it clear he was a Mongolian king."