Did Chinese explorers land before Columbus?

From the Lynchburg (Va.) News Advance:

Charlotte Rees is heiress to evidence that could turn world history upside down - if she can corroborate it. She and her six siblings inherited maps from their father, a third-generation missionary born in China, that she says may show the Chinese had discovered America - and the rest of the world - as early as 2200 B.C. “I’m ready for opposition,” said Rees, who lives in Forest. “Even when Columbus was saying the world was round, he had opposition.” Rees, 59, will propound her theory Monday at a symposium at the Library of Congress in Washington, D.C., on Zheng He, an early Chinese explorer. In addition to the maps, which depict lands that she argues could be North and South America, Rees says there is other evidence of a Chinese presence more than 3,700 years before Columbus set foot here.

The Desert (Calif.) Dispatch also carries an article:

For more than a decade, seven fragile map books sat under Hendon Harris' bed battling dust and darkness. Two years ago they were exhumed and could possibly prove the Chinese discovered the American land mass 4,200 years ago. "These maps were under my bed for 10-plus years, because we really didn't know what we had," said Hendon Harris, an Adelanto developer who owns several apartment buildings and is a prime sponsor of the Adelanto Boys and Girls Club. He's also building a strip of stores off Bellflower Street and Bartlett Avenue. Harris said the maps depict giant redwood trees, the Grand Canyon and show America as a land 3,300 miles wide. "And that is within a few miles" of the nation's true width, he said. The maps were discovered by his father Dr. Hendon M. Harris, a third generation Baptist missionary, in a South Korean antique shop in 1972, he said. The maps were the focal point of a book he self-published, entitled "The Asiatic Fathers of America."