Central China, 1304 AD. Hou-Ming is a city of ghosts on the shores of a giant lake, a vast graveyard for victims slaughtered by invading Mongol hordes.

Amid the ruins, three Chinese children meet and forge a friendship that will change their lives.

So begins The Mandate of Heaven, the third and concluding part of Tim Murgatroyd's powerful trilogy of novels set in medieval China.

His first novel, Taming Poison Dragons, was a moving and beautifully written account of the life of an idealistic Chinese poet in 12th century Song dynasty China.

From a retreat in the mountains of western China Yun Cai, the central character, looks back on his life and recalls lost love, his stubborn refusal to conform to convention and the terrible price he paid.

Murgatroyd, a schoolteacher in York, had never been to China and could not speak a word of Chinese. All he knew about the country came from the Chinese poems he had read and loved in English translations.

Yet his account of the life of a fictional Song dynasty poet was so convincing it persuaded University of Sheffield academic Dr Lily Chen to translate it into Chinese and it was published by a leading Chinese publisher late last year.

The second novel in the trilogy, Breaking Bamboo, was set 60 years or so later as Kublai Khan's Mongol army swept down from the north to engulf Song China in fire and turmoil. It follows the lives of two of Yun Cai's grandsons - one a soldier, the other a humble doctor - as their world changes around them.

That, too, has been translated into Chinese, and is due out there later this year.

Mandate of Heaven begins 40 years or so after the events of Breaking Bamboo and brings the trilogy to a conclusion.

Hou-Ming, a great - and fictional - Chinese city, lies in ruins with much of its population slaughtered.

"It has been virtually depopulated by the Mongols," says Murgatroyd. "They had this policy that if you resisted, everybody would die." Hou-Ming did resist the Mongol advance and paid the price.

Amid the ruins, and on the shores of the great lake, three children struggle to survive.

Yun Shu, the granddaughter of the young doctor in Breaking Bamboo, has been cruelly rejected by her family for refusing to have her feet bound.

Teng is an artist and scholar, the son of a noble family that once ran Hou-Ming, and which decided on the disastrous policy of resistance against the Mongols. The family has been destroyed and Teng reduced in status to little better than a beggar. Hsiung is a servant boy enslaved by the Mongols who thirsts for revenge.

The novel follows the three over a period of 20 years as they grow to adulthood and each finds their own way of surviving in their harsh new post-apocalyptic world.

Yun Shu becomes a Daoist nun, Teng an artist and scholar and Hsiung a ruthless rebel warlord determined to drive the Mongols from his native land.

"The big theme is about how does a culture try to survive - how do human beings and the human spirit endure through all the trials that history throws at them?" Murgatroyd says.

There is a love story running through this epic tale of human survival and a twist at the end that the 47-year-old author hopes brings the trilogy to a satisfying conclusion.

Finishing it came as quite a wrench. "I've spent years on this project. It has been a big chunk of my life," he reveals.

But a real privilege, too, he says.

Murgatroyd researched extensively into Chinese history while writing the books. "It has been a real joy and delight. I've learned so much about one of the most wonderful cultures in the world."

The Mandate Of Heaven is published by Myrmidon, priced £16.99. This article first appeared in the York newspaper The Press, www.yorkpress.co.uk.