Stores along so-called 'Korean Street' in Dandong carry billboards advertising Korean products, including ginseng and kimchi. In some stores, Korean TV stations are received by satellite. Wang Jing / China Daily

According to Liu Feng, a senior official with the Dandong border police, more than 4,000 people from the DPRK live in the city. They work in a variety of industries, including catering, clothing and information technology.

A 47-year-old businessman, who gave his name as Mr Li, said he has been working in Shenyang as the representative of a DPRK company for about three years.

Although Li didn't wear a Kim Il-Sung pin, the almost-obligatory lapel pin emblazoned with the head of the former DPRK leader, his pompadour haircut made him stand out in the crowd. Apart from that, he looked like any other businessman in Dandong - smartly dressed in a black jacket and talking rapidly into his Samsung cell phone.

"I have been traveling between Shenyang and Dandong a lot recently," he said. "My 18-year-old son is studying at Northeastern University in Shenyang."

'Korean Street'

A five-minute walk from the Sino-DPRK Friendship Bridge - one of the main links for autos and trains traveling between the two countries - is "Korean Street", a 500-meter stretch that crosses the city's busiest district. Most of the stores carry billboards advertising Korean products, including ginseng and kimchi, in both Chinese and Korean, although some are in Korean only.

In the restaurants, customers sat cross-legged on cushions on the floor in traditional style, chatting in Korean. In the backs of some of the shops, a satellite feed of the Korean Broadcasting System, the biggest of the four TV networks in the Republic of Korea, was being shown constantly.

Lu Yongchun is a member of the local Korean ethnic group, one of China's 55 minorities. Around 1.9 million ethnic Koreans live in China and more than 16,000 of them live in Dandong. Many of the city's residents enjoy a Korean lifestyle and speak the language, factors that have helped Dandong become China's biggest trading point with the DPRK, Lu said.

"My parents spoke only Korean at home," said the 45-year-old Lu who has been running a company for nine years. "I didn't learn to speak Chinese until I was enrolled at elementary school."

Lu's company, which imports DPRK coal, which is 3 to 5 dollars cheaper per metric ton than the domestic product, employs 200 staff.

"People from the DPRK only deliver after payment in full. The business model is a little risky for purchasers, but after years of cooperation, I have some solid and reliable suppliers," he said.

Dandong's cargo port stands within a 10-minute walk from the Yalu River. "Every day, roughly 200 lorries loaded with goods from here will cross the bridge into the DPRK", said an official who is doing the passport check for people going through the port.

Although the Sino-DPRK Friendship Bridge is mainly intended for railway traffic, it also has a one-way road, which means incoming and outgoing traffic has to be carefully regulated. Sometimes, there are so many DPRK-bound trucks waiting on the roads leading to the bridge that the lines stretch back into Dandong's busy commercial streets.

According to a recent report from Dandong Customs, the value of the imports and exports coming through the port reached about $4 billion in 2013, a rise of 11 percent from 2012.

Zhou Zheng has been conducting business with partners from the DPRK for more than 10 years. Situated near the Yalu River, the 49-year-old Dandong resident's company mainly exports mining equipment and technology, machinery and iron ore to the DPRK, and in return imports raw materials, mainly non-ferrous metals.

"We trade a wide variety of products. Sometimes, business delegates from the DPRK also entrust us to procure chemical and textile products, household appliances and so on," he said.