If you double-check the title of this voluminous book in order to confirm that the year mentioned is indeed 1421, you may conclude that history is being rewritten and that Chinese seafarers discovered America 70 years before Christopher Columbus. You might say: Wait a moment! Is Gavin Menzies trying to tell us that everything we learned about the discovery of the New World in history textbooks is wrong?

Menzies, a retired British naval officer, is convinced that he is right and believes that he is backed by evidence. He spent 15 years researching materials for the book. When it was first published in the Europe last year, the book made a splash with a well-organized advertisement campaign. When it was published in the United States in early 2003, critics and readers were curious about such a claim. But in the United States, the name Christopher Columbus is carved solidly in rocks and Americans know who discovered their continent. To all those who doubted his book, Menzies responded by saying that he has amassed "massive" evidence to support the theory that in fact Chinese adventurers came to America's shores well before Columbus. The Ming dynasty that ruled China in the 15th century was known to have shipyards that produced hulking vessels measuring 135 meters in length, made with the best teak wood in the world, with as many as nine masts. China was a naval power at the time and its desire to conquer the world and expand the power of the Middle Kingdom was boundless. On the other hand, ships built in Europe in the later part of the 15th century measured only about 30 meters long. Those were the ships used by Vasco de Gama to ply the oceans and by Columbus to reach America.

Menzies claims in his book that eunuch Admiral Zheng He, a loyal official in the court of Emperor Zhu Di, was ordered to set sail in 1421 on a mission to the ends of the earth and to collect tributes from barbarian countries for the Chinese emperor. Zheng, who was known as "Sin Bao", wrote about his adventures in the seven seas of the world and became a legendary figure in Western literature under the name of "Sinbad the Sailor." Zheng was the commander of the Treasure Fleet, which was composed of a large number of impressive vessels.

During extensive interviews with US media when his book was published, Menzies told The New York Times, "Zheng set sail in 1421. The famed Treasure Fleet was five times larger than Columbus's caravels. Each held a thousand men. Two years later, in 1423, seven ships returned. Then, in a decision that would change all of history, the Ming emperor ordered all the ships dismantled. He pensioned off the sailors. And he burned all the records."

Historians agreed that in 1423, after the Treasure Fleet reached the area that is modern-day Kenya and returned home, the Ming emperor decided to end all exploration voyages. But Menzies claims that the Treasure Fleet went farther than Kenya, eventually rounded the Horn of Africa and crossed the Atlantic to discover America.

Historians agree on a few other facts mentioned by Menzies, including the arrival of the Chinese fleet in Calcutta in 1421. Menzies claims that Zheng had a world map that he used to travel all the way to America and that Columbus somehow got hold of that map, allowing him to discover America long after Zheng. It has also been reported that when Columbus reached what he believed to be America, somewhere in the Caribbean, the first people he met were Chinese. Is this part of legend or history? No one knows.

The publication of this book, which contains a good deal of photographs, maps and other descriptions, has delighted many people in mainland China. Reportedly a Chinese admiral has announced that he will build a replica of the Treasury Fleet and sail it around the world. More than 10 years ago, Spain built replicas of the vessels used by Columbus and sent them to America. History may dispute Menzies's story, but for readers it is as interesting as the adventures of Sinbad the Sailor.