Bac Ha is a town of about ten thousand people in Lao Cai province, in the mountains of far northern Vietnam, about thirty kilometers from the Chinese border. On Sundays, beginning at dawn, its population roughly triples.

The Sunday market is the largest in the region. It draws traders and buyers from at least a dozen surrounding villages, many of them Flower Hmong, named for the bright embroidery on the women's skirts and headscarves.

The market has several sections. There is a textile section, a vegetable section, a section for cooked food, a section for live chickens and ducks, and, on the upper edge of the town near the football field, the cattle market.

The cattle market is where the real money moves.

On a Sunday in early May, the morning began with fog. The town sits at about nine hundred meters elevation, and at six in the morning the fog had settled into the bowl of the valley and was just beginning to lift.

The first traders arrived at five-thirty, leading water buffalo down dirt roads from villages with names like Ban Pho, Na Hoi, and Ta Chai. By six the cattle market field, an open patch of red earth about the size of a soccer pitch, held perhaps eighty buffalo, twenty cows, and a small cluster of horses.

Vang A Sung, a Flower Hmong trader from Ban Pho, had brought two buffalo. He is forty-four. He has been bringing buffalo to the Sunday market since he was nineteen.

"The big one is for selling," he said, through a translator. "The small one is for showing. So the buyer knows I have more at home."

The big buffalo, a five-year-old male, was tied to a wooden stake driven into the red earth. Vang A Sung sat on his heels beside it, smoking a long thin pipe, watching the buyers walk past.

Buyers move slowly. They look at the animal's teeth, feel its shoulders, run a hand along its spine. They squat down beside the trader. They are offered a cigarette, which they sometimes accept.

“They look at the animal's teeth, feel its shoulders, run a hand along its spine.”

The price negotiation begins, always, with a number that is too high. Vang A Sung's opening price for the five-year-old was forty-two million dong, about sixteen hundred U.S. dollars. The first buyer, a man from Si Ma Cai, offered thirty.

They settled, after about twenty minutes, at thirty-six.

The deal was closed with a handshake and a small cup of rice wine, which Vang A Sung poured from a plastic bottle he carried in a cloth bag. The buyer drank, Vang A Sung drank, and the money, in a stack of orange five-hundred-thousand-dong notes, changed hands.

"It is fast now," Vang A Sung said. "When my father sold, it took longer. There was more talking."

The Flower Hmong are one of several Hmong subgroups in Vietnam, distinguished by the bright pink, orange, and green embroidery on their traditional clothing. The women wear pleated skirts that flare like flowers when they walk, and headscarves wound high.

On Sunday mornings the market is a wall of color. The women's skirts catch the early light and seem, at a distance, to move independently of the bodies inside them.

The textile section, downhill from the cattle market, sells the embroidery itself, both as finished garments and as long strips of pattern that women buy and sew into their own skirts at home.

I bought a strip from a woman named Mai, who was about fifty and who told me, through the same translator, that she had made it herself over the course of three winter evenings. It cost the equivalent of nine U.S. dollars.

"For a foreigner," she said, smiling, "the price is the same as for a Hmong. I do not change it. But you should know I would have made it anyway."

Bac Ha's Sunday market has become, over the past fifteen years, a fixture of the northern Vietnamese tourist circuit. On a typical Sunday in season, perhaps three hundred foreign visitors come up from Sapa or down from Hanoi to walk through it.

The cattle market is less affected by this than the textile market. The buyers and sellers of buffalo do not, on the whole, sell to tourists. The economy of the cattle market is the economy of the surrounding villages, where a water buffalo is still the primary draft animal for the rice terraces.

"The tourists," Vang A Sung said, watching a small group of them walk past with cameras, "they take pictures. They do not buy buffalo."

He laughed at his own joke.

By eleven the cattle market was thinning. Most of the buffalo had been sold or led home. Vang A Sung's small buffalo, the one for showing, was tied to the back of a motorbike taxi for the trip back to Ban Pho.

Before he left, he bought, from a woman at the cooked food section, two small bowls of thang co, a Hmong soup made from horse meat and offal, seasoned with cardamom and star anise. He ate one and brought the other home, in a plastic bag, for his wife.

The fog had lifted entirely. The valley below the town was visible now: terraced fields, red roofs, a thin river running south.

Next Sunday, Vang A Sung said, he would bring three buffalo. Possibly four.