In our week-long drive, security was tight - we often couldn't stay to chat for long. But people told us they have interacted for years with North Koreans across the river.
North Korea is a closed country, which makes it easy to forget that North Koreans and Chinese have long crossed each other’s borders. In the 1960s, people ran from China to North Korea. Then in the 1990s, they travelled in the opposite direction.
Both times, the reason was the same: hunger.
The border is the gateway for most of North Korea’s trade with the outside world. That also makes it the main channel for Beijing to put pressure on Pyongyang.
On our journey, we learned of some surprising ways people on both sides of the frontier turn to each other for subsistence, social gatherings and trade. Also, most of the 31,000 or so North Koreans who have defected to the South came through this border, South Korea’s government says. In a final chapter, our colleagues in Seoul share some of the dramatic stories defectors told us after they had crossed the river.
There are about 25 million North Koreans, and 15 official crossing points on the frontier. The Chinese have tried to limit arrivals from the North. But the border is 1,400 km (880 miles) long. In places, the ways through are clear to see.
In the picture above, the barbed wire is held back by a rag to allow someone through. In some ways, that encapsulates China’s equivocal response to its problem neighbours.
If Beijing were to cut ties too sharply, that could destroy North Korea and unleash an exodus of millions. On the other hand, being too welcoming could have a similar effect.
On our journey we worked in public spaces. There were no restrictions on our reporting although at some points, Chinese police turned us away. After we had both driven the length of the border in November, I returned to some sites in March.
An ice patrol
The guard was watching two women wash clothes in the freezing water beneath him.
“North Koreans do all kinds of things in the river - they wash vegetables, they wash clothes, they wash themselves,” said Mr. Sun, a timber trader who didn’t want to give his first name, as we watched a group of women crouching on the ice with tubs of clothes.
The sight reminded Damir of an earlier assignment. He had asked a North Korean man what he was most afraid of. The answer was not as he expected.
“Cold,” the North Korean said. “I can handle anything. But not the cold.”
Women’s daily chores
We saw scenes like this throughout the trip. People have to break the river ice to get on with their daily lives. Sometimes the women didn’t wear gloves.
North Korea was once wealthy. In the 1930s, when Korea was a Japanese colony, Japan invested heavily in industry in the North, making it the next most advanced industrial region in East Asia, according to Andrei Lankov, a North Korea expert. When the Korean peninsula was divided up after World War Two, everything in the North came under the control of Kim Il Sung.
Lost in geopolitics
In 1950, the North invaded the South. China and the Soviet Union backed the North, and the United States bombed the bridges here that China used to supply North Korea.
Later, in the 1960s, Chinese nationals went to study in North Korea: “Their education system was far superior to ours,” said Li Zhonglin, a China-North Korea specialist at Yanbian University. “Some didn’t come back. They stayed there and probably now regret not coming back.”
Since North Korea started testing nuclear weapons in 2006, it’s been under international sanctions. As its nuclear programme stepped up, so have the sanctions, and tensions with China have risen.
“Their beer is better”
Trade between China and North Korea has fallen dramatically because of sanctions, but the U.N. has not sanctioned essentials like food.
Towards the end of the day in Tumen, we watched these women cross into China from North Korea.
Tumen is in Yanbian, an official Korean autonomous region which people call “the third Korea” because around half the two million Chinese of Korean descent are registered there. There is a small missionary community in Yanbian - mainly South Koreans, Americans and Europeans. Some of them help North Korean defectors.
At the other end of the border in Dandong, just about everyone is somehow connected to North Korea - whether through their relatives who do business with North Korean trade representatives, or because they eat at restaurants staffed by North Korean waitresses (they are invariably women) or study alongside North Koreans at Eastern Liaoning University.
There are seafood and textile factories which employ North Korean workers, and shopping centres that cater to North Korean customers who are mostly looking to bulk-buy products to take back to North Korea to sell.
One man we met in Hekou, near Dandong, said he and his friends still cross to the North sometimes for late-night drinking sessions. He spoke on condition we didn’t name him.
“We drink all night, it can get pretty rowdy,” he said, puffing on a cigarette. “It’s fun.”
“You have to bring four things: Roast chicken, sausage, baijiu (Chinese alcohol) and cigarettes. All four are essential. We don’t bother bringing beer – their beer is better than ours.”
After we saw this North Korean man cycling in front of a decorated barrier in Hyesan, the locals told us it was new. Some speculated it was put up to hide North Korea’s poverty from people over the river, but we couldn’t get into North Korea to find out more.
Older people here say they still remember China’s “War to Resist U.S. Aggression and Aid Korea,” fought between 1950 and 1953. After Japan's defeat in World War Two, the Korean Peninsula was divided in half. In 1950, the North invaded the South, starting the Korean War which was paused by a truce in 1953 and has left the two Koreas separated to this day. Some bridges, like this one in Hekou, are still in ruins.
Not far from here, in Dandong, a retired truck driver called Wang Bingmin said that as a child, he lived by the bridge before it was bombed, and remembered playing there while the bombers flew overhead.
Everyone fled, he said. Even the mountains were bombed.
“People’s intestines were splattered all over the trees.”
He brings a pet squirrel to the banks of the river every day. He said it helps with his insomnia.
North Korean firewood
Yang Shilong sells souvenirs by this wrecked bridge. During winter, he said North Koreans will walk over the ice and take wood from the pillars.
“They burn it to keep warm,” he said, packing plastic boxes of unsold souvenirs into his car at the end of the day. “The Chinese aren’t allowed to take the wood.”
When the river freezes over, people say it also gets easier to cross back and forth.
Next to the bridge, banners exhort people to “prevent and quash any smuggling,” and say it is forbidden to launch drones, fly drones or use drones to take photos.
No socialism here
The swing is supposed to be a spot for tourists to sit and observe the other side but it is rusty and hangs at an odd angle.
“That’s North Korea over there, it’s a different country,” says fisherman Mr. Wang, who didn’t want to give his first name. “They’re socialist, they’re not like us.”
Chinese fishermen work their small boats near the North Korean side.
Of trade and towers
There are watchtowers like this all along the river banks. Both Chinese locals and North Korean defectors say the North Korean secret services - the bowibu - keep an eye on people’s comings and goings from them.
Some also say the bowibu have a hand in illicit trades across the frontier, although these dealings are becoming harder now than they used to be. The North Korean mission to the United Nations didn’t respond to a request for comment.
“You wouldn't believe the kinds of things that used to be illegally traded,” said Mr Sun, the timber trader. “In the early 2000s, the North Koreans used to sell bear claws.
"No one would dare sell Chinese bear claws - that's a serious crime.”
Law and order
The sign says, “take the initiative to preserve order along the border.” The Chinese side is dotted with surveillance cameras and red banners. Some are covered with slogans like “the motherland’s interests supersede all else.”
China has long stationed military and police here, partly out of fear of refugees. And in recent years, Chinese media have told of Chinese villagers killed by North Koreans sneaking across the border, often in search of food.
On the way here, two southern Chinese businessmen told me they were heading to Dandong to try to recruit cheap North Korean factory workers to make electronic components.
They currently use prison labour from jails around China because the quality of the products is better and the salaries are lower than for ordinary factory workers, one said: “But we’d rather source directly from North Korea because it’s even cheaper.”
The men said their competitors starting using North Korean labour several years ago and have done very well because of the amount they've saved on labour costs.
Since United Nations sanctions were stepped up in 2017, North Korean workers are in short supply. “I hear it’s been very strict recently,” the businessman said. “But I think things may be easing up.”