They met as children diving for fish when their countries, China and North Korea, touted a relationship as close as "lips and teeth" and when neither thought getting rich was glorious.
Now Chinese fisherman Xiao Yong smuggles food and items considered mundane in his own country to grateful old friends across the border, including a North Korean sweetheart he regrets he cannot marry.
The 31-year-old regularly crosses a muddy branch of the Yalu River separating north-east China from its famously hermetic neighbour, bribing his way past rifle-toting border guards with cash and cheap alcohol.
"My friends, now farmers and even soldiers, live bitter lives over there. It's like China under Mao Zedong," Yong said, standing astern while navigating his metal dinghy over the stream he knows so well.
"Some of them nearly starved to death during the famine in 1995, when people jumped over the border in waves. North Koreans, especially young girls and boys, still come over, even though it's a little harder now," he said.
The porous, unguarded border - in some places the river is no wider than a stone's throw - has proved irresistible to hundreds of thousands of North Koreans fleeing hunger, poverty and political persecution, aid workers say.
Activists say that up to 300,000 North Korean refugees are hiding in north-east China after fleeing hunger, poverty and repression in their Communist homeland.
Residents say security on the watery border has been tightened since 2002 when US officials said North Korea had confessed to building a secret nuclear programme in violation of an international agreement.
But it's easy for Chinese, including smugglers and human traffickers, to cross illegally into North Korea, they say, and this props up a thriving black-market border trade that helps keep the barren North Korean economy afloat.
Dandong natives such as laid-off factory worker Lao Zhou, whose picturesque home town draws tourists eager to spy on North Korea with telescopes, shake their heads when they talk about refugees.
"North Korean women make good wives. They are beautiful and hard-working," he said, echoing an oft-repeated view. "It doesn't cost much to buy a North Korean girl for a wife and just a few thousand kwai (hundreds of dollars) to get them a residency permit."
Refugees who cross the border near Dandong, which residents say is awash with North Korean agents posing as waiters and restaurant owners, usually make their way to the ethnic Korean autonomous region of Yanbian in north-east China.
Lucky ones are taken in by kind families, many of them Christian, and melt into the fabric of a familiar society speaking traditional Korean, a dialect their South Korean cousins find quaint.
Just as likely, activists say, unprotected refugees constantly look over their shoulder for fear of deportation and are often forced to work in construction or prostitution to pay back debts accrued during their risky journey to China.
China, which fought alongside North Korea during the Korean War in the 1950s, considers them illegal migrants, not refugees, and has an agreement with its neighbour to repatriate them.
"It's unreasonable," a China-based Korean activist said of Beijing's policy of viewing North Koreans as economic migrants.
Overseas Christian and rights groups encourage North Koreans to seek asylum at foreign embassies and consulates across China in the hope of bringing down the Pyongyang government through an exodus of refugees.
Hundreds of North Koreans have been rounded up and sent back. Defectors say these face imprisonment, torture or death.
Activists lobby US officials to place human rights higher on the agenda during the next round of talks in Beijing to defuse the nuclear crisis in North Korea, saying the United States has already earmarked $20 million to set up camps along the border.
To avert Western criticism, China has allowed hundreds of North Korean asylum seekers, who have stolen into embassies and foreign schools in Beijing since last year, to go to South Korea through third countries such as the Philippines and Thailand.
Occasional smugglers such as Xiao Yong say Dandong will continue to draw North Korean refugees until the Pyongyang government collapses or unleashes China-style reforms.