Chinese executives say that Chinese workers are not always less expensive, but that they tend to be more skilled and easier to manage than local workers. “Whether you’re talking about the social benefits or economic benefits to the countries receiving the workers, the countries have had very good things to say about the Chinese workers and their skills,” said Diao Chunhe, director of the China International Contractors Association, a government organization in Beijing.

But in some countries, local residents accuse the Chinese of stealing jobs, staying on illegally and isolating themselves by building bubble worlds that replicate life in China.

“There are entire Chinese villages now,” said Pham Chi Lan, former executive vice president of the Vietnam Chamber of Commerce and Industry. “We’ve never seen such a practice on projects done by companies from other countries.”

At this construction site northeast of the port city of Haiphong, an entire Chinese world has sprung up: four walled dormitory compounds, restaurants with Chinese signs advertising dumplings and fried rice, currency exchanges, so-called massage parlors  even a sign on the site itself that says “Guangxi Road,” referring to the province that most of the workers call home.

Image Chinese workers at a thermal power plant construction site in Trung Son, Vietnam. Credit... Shiho Fukada for The New York Times

One night, eight workers in blue uniforms sat in a cramped restaurant that had been opened by a man from Guangxi at the request of the project’s main subcontractor, Guangxi Power Construction Company. Their faces were flushed from drinking Chinese rice wine. “I was sent here, and I’m fulfilling my patriotic duty,” said Lin Dengji, 52.

Such scenes can set off anxieties in Vietnam, which prides itself on resisting Chinese domination, starting with its break from Chinese rule in the 10th century. The countries fought a border war in 1979 and are still engaged in a sovereignty dispute in the South China Sea.