The Promised Land.(Guangzhou's Canaan market)

Joseph Nwaosu, a Nigerian exporter, has yet to acclimate to the winter damp of Guangzhou, on China's southern coast. Over a button-down shirt he usually adds a heavy brown turtleneck sweater and a rumpled tan parka; when necessary, he wears a wool hat. The layers help with his commute. From his apartment, which has a mattress on the floor and rents for forty dollars a month, it takes an hour by bus and a half hour on foot to reach his office, across the street from the Canaan Export Clothes Trading Center, a half-lit market painted a dusty shade of peach. Almost all its customers are merchants from Nigeria, Mali, Ghana, and other African countries. They are arriving in such large numbers that in November Kenya Airways inaugurated mainland China's first non-stop route from Africa, between Nairobi and Guangzhou. Since the Canaan market opened, six years ago, similar markets, filled with African buyers and Chinese sellers, have arisen along the same block. Taxi-drivers call the neighborhood Chocolate City.

The Canaan market opens onto Guangyuan West Road--eight roaring lanes of cars and trucks and scooters on the ground and four more lanes in the air, on concrete spans that block the rain and the sun. Every square foot has been claimed by commerce. Walking to and from work, Nwaosu (I have changed his name) traverses a sidewalk offering a sharpening stone for cleavers, a handheld sewing machine, a mobile-phone card for Africa, an hour of sex, a bundle of socks, an electronic songbird that sings, an eight ball of cocaine, a mold that makes the perfect dumpling. Lining the sidewalks are passport-photo booths, mobile-phone venders, and shops crammed with jeans and T-shirts, alligator-skin cap-toe shoes and made-to-measure suits, soccer jerseys and bulletproof vests (four hundred and ten dollars for blue nylon; five hundred and fifty-six dollars for camouflage). But the real business goes on inside, where merchants cut deals for bogus and factory-reject Prada and Lacoste and Polo. The Canaan economy is all cash and unhindered by borders: "one hundred per cent human hair" extensions are clipped from heads in India, braided by hand in China, and packed for sale in West Africa. The man selling them was, until recently, trading motorbike parts in Singapore, and if the hair business slows down he will move on again. All of Canaan seems determined to get somewhere else.

Nwaosu, at twenty-nine, is spindle thin, with a wary flicker in his eyes. He works out of a tiny, windowless office above a strip of clothing stalls a few hundred feet from the original market. "When I arrived in Guangzhou, this was the first place I came," he said one recent afternoon. Outside the open office door, a stereo was thumping, and someone was straining to seal an overstuffed container of clothes. Inside, ducts and wires slumped from an open ceiling. On one wall--a metal garage door--someone had scrawled a phone number for takeout. The other walls had been covered in leopard-print contact paper. The sole decoration was a large calendar featuring a smiling young Nigerian priest. It had a Scripture citation for every date and an exhortation across the top: "READ THE BIBLE IN ONE YEAR!"

Nwaosu's glasses, metal-framed and often askew, give him a professorial aspect that is rare in the world of the traders. He did not set out to be a businessman in Guangzhou. He had always planned to be a priest. His parents were teachers, with eight children. He studied philosophy at Imo State University, in the Igbo country of southeastern Nigeria. When he was twenty, he joined the seminary. But he developed kidney problems that left him tired and in pain. Because the work of a priest is physically demanding, the seminary asked him to withdraw. "I was devastated," he told me.

He had little confidence in Nigerian hospitals, and doctors told him that treatment would cost at least ten thousand dollars. "But my family couldn't pay that," he said. "I felt like I was going to die the next day. For a whole year, I had no money--I had no bills, no copper. I wrote to the Ford Foundation. But they said they only help groups, not individuals. So I decided I will help myself."

A friend lent Nwaosu cash to buy a mobile-phone card, and he and his sister began charging people to make calls. They moved up to selling the cards, and by the spring of 2006 he had saved enough to consider going abroad. "At first, I wanted to go to Germany," he said. "But the Embassy wouldn't give me an appointment. I tried Holland, but that didn't work." Getting a Chinese visa was far simpler. He paid more than eight hundred and fifty dollars to an agent in Lagos, and a month later he boarded an airplane for the first time in his life, bound for Beijing. When he landed, he hailed a taxi, but he did not know to ask for the meter to be turned on. "It should have been thirty yuan. He charged me four hundred and fifty," he said.

Medical care in China was inexpensive, and Nwaosu was successfully treated for his ailment, but when he was unable to make a living in Beijing he headed south to Guangzhou, the trading port formerly known as Canton. He had nothing but the scribbled number of a stranger--a soft-spoken Nigerian trader who had arrived four months earlier. "He taught me the nature of the place," Nwaosu said. "The most important thing he taught me was to believe in myself--and to believe in God, too."