Up to their ankles in mud, hundreds of Rohingya refugees fought to the front of the crowd outside of their makeshift camp. An open-bed truck full of Bangladeshi volunteers was passing by, tossing out donated goods at random: small bags of rice, a faded SpongeBob SquarePants T-shirt, a cluster of dirty forks.

Entire families sloshed through the rain hoping to grab whatever they could. One boy, no older than six, squeezed his way to an opening where a pair of oversize men’s jeans came hurtling off a truck. He had to fight off an older boy before he could run off with the prize.

There were already more than 200,000 ethnic Rohingya migrants stuck in camps like this one, Balukhali, in southern Bangladesh. But over the past month, at least 500,000 more — more than half of the Rohingya population thought to have been living in Burma — are reported to have fled over the border to take refuge, surpassing even the worst month of the Syrian war’s refugee tide.

As international leaders squabble over whether to punish Burma for the military’s methodical killing and uprooting of Rohingya civilians, the recent arrivals are living in abjectly desperate conditions.

This is not so much a defined camp as a dense collection of bamboo and tarp stacks. When I visited, children were wandering in the mud looking for food and clothes. There are worries about cholera and tuberculosis. With no toilets, what’s left of the forest has become a vast, improvised bathroom.

While the flow of refugees has greatly slowed in the past week, aid organisations are still overwhelmed.

“It’s on a scale that we couldn’t imagine,” said Kate White, the Doctors Without Borders medical emergency manager in Bangladesh. “This is a small piece of land, and everyone is condensed into it. We just can’t scale up fast enough.”

For decades, the Muslim Rohingya of Burma, a minority concentrated in the western state of Rakhine, have faced systemic repression by the country’s Buddhist majority, and particularly by the military. But what happened in August, when the military and allied mobs began burning whole Rohingya villages, was so much worse that the United Nations (UN) is calling it ethnic cleansing.

Across the camps, the escaped all have accounts of fire and cruelty.

Anwar Begum, 73, sat on the ground, her arm limp below the elbow. She was in constant pain and could hardly focus her eyes. The army, she told me, set fire to her village in Burma and cleared the people out. As the civilians fled, one soldier singled her out, saying, “You’re not welcome in Burma,” and smashing her elbow with the butt of his rifle. As her family dragged her away, the soldier had one last thing to say: “Bring that to Bangladesh.”

What was once a loose network of camps has become a sprawl. Acres upon acres of forest have been razed to make way for small cities of huts, made from cheap black tarps covered in mud. Across the camp, men are building them as fast as they can.

Every medical treatment post here has a line that snakes nearly around the camp. Local doctors and foreign aid organisations like Doctors Without Borders are scrambling to set up more clinics but can hardly keep pace.

With just one main road connecting most of the district, aid groups are struggling to reach the most remote camps. In Taink Khali, a nearly 30-minute hike off the main road, an Australian aid agency called Disaster Response Group was setting up a mobile clinic in a tiny shack. Dozens of women and children were waiting quietly in the hot sun.

“We’re the first aid these people have seen,” said Brad Stewart, operations manager for the aid group, a small medical assistance organisation that most often serves backpackers in Nepal. His team of four ex-military Australians were taping a bottle of hand sanitizer to a tree.

“The immediate attention is going to the more established camps,” he said. “Out here, we’re just a drop in a very large bucket.”

The hundreds still coming face a dangerous boat ride across the river border into Bangladesh. On Thursday, dozens of Rohingya, many of them children, were killed as a trawler carrying them capsized in the Bay of Bengal.

Their bodies washed up on the bay alongside some survivors.

“The women and children couldn’t swim,” said Nuru Salam, 22. He had tried to cross with his entire family when the boat tipped in the sea. His son had died and he was waiting to find his wife’s body. “There are still many more bodies to come.”

The physical challenges here are steep enough. But the Rohingya crisis has shaken the entire region, exacerbating already severe sectarian and political strains and worsening the relationship between Bangladesh and Burma, in particular.

This is not the first wave of Rohingya that Bangladesh has had to absorb. In 1978, around 200,000 Rohingya fled into the country. Most returned to Burma after the two governments hammered out a repatriation deal. Another influx came in the early 1990s, as well as in 2012 and in October 2016.

Even before this latest exodus from Burma, the stresses being placed on this already poor country were considerable. Yet some of the locals have shown remarkable kindness.

“I see that the host community here has been incredibly positive,” said Karim Elguindi, head of the World Food Programme’s office in Cox’s Bazar, Bangladesh. “I’m still surprised by the humanitarian response of the government and the community.”

Elguindi has worked in Darfur, the strife-torn region of western Sudan, and he noted that while the sheer concentration of arriving Rohingya was unprecedented and the terrain challenging for aid distribution, the Rohingya could at least count on basic security once they made it to Bangladesh.

“Compared with Darfur, here they speak the same language,” he said. “The refugees in Darfur were in IDP camps,” referring to internally displaced persons. “They were still among enemies. Here, they are relatively safe.”

With existing camps beyond their capacity, the Bangladeshi government is racing to convert an additional 2,000 acres of land into settlements for the new arrivals. But a report from a network of UN agencies warned that Rohingya refugees had already arrived at the site before adequate infrastructure and services had been set up. Local authorities have begun limiting Rohingya refugees to the camps, setting up police checkpoints to prevent them from leaving.

On Sunday, a Bangladeshi Cabinet minister said that the government did not plan to give refugee status to the newly arrived Rohingya — a stance that is complicating efforts to get them more aid. The Bangladeshi government has said it hopes that Burma will eventually take back the Rohingya.

The Burmese government, however, has said that it will only repatriate those with the correct documentation to prove they are from Rakhine. It is unlikely that most of the Rohingya who recently fled to Bangladesh brought such papers with them, if they ever possessed them at all.

So far, the bulk of the aid effort has fallen to groups of Bangladeshi volunteers. Touched by the stories they have seen on local television, many across the nation have started donation campaigns and driven long distances to give what they can to struggling refugees.

“We couldn’t just sit at home,” said Abul Hossain, a volunteer who lives six hours north of the camps. “Last week we asked everyone in our village to donate. We drove all night to bring it here.”

Hossain and his neighbours had hoped to hand the goods over to government workers or foreign aid organisations like the UN, but they say they have not been able to find any.

“We’ve been driving around since the morning looking for anyone to take this,” he said. “So now, we’re just handing it out ourselves.”

This has proved a dangerous method. Last week, CNN reported that a woman and two children were killed in a stampede as a group of Bangladeshis threw food from a truck.

Since then, assistance has improved significantly. Food distribution points have been set up by the Bangladeshi government to try to lessen the need for the volunteer truck visits. But it is still a challenge.

“There are no roads. We’ve been carrying our equipment in the heavy rain,” said White, from Doctors Without Borders.

Rohingya refugees – in pictures Show all 15 1 /15 Rohingya refugees – in pictures Rohingya refugees – in pictures A young girl and a baby wade through mud after arriving in Whaikhyang, Bangladesh from Burma on 10 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees walk through a camp in Whaikhyang, Bangladesh after arriving from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures A young Rohingya refugee gathers firewood after arriving in Whaikhyang, Bangladesh from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees wait for sacks of rice to be distributed in Whaikhyang, Bangladesh Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees arrive on a boat in Whaikhyang, Bangladesh after crossing from Burma on 8 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees react after being re-united with each other after arriving in Whaikhyang, Bangladesh on a boat from Burma Getty Rohingya refugees – in pictures Rohingya Muslim refugees walk along the remains of a road after arriving in Whaikhyang, Bangladesh on a boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Myanmar Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees stand in the rain after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Indian children hold placards and shout slogans during a protest against the alleged persecution of the Rohingya Muslims in Burma EPA/Raminder Pal Singh Rohingya refugees – in pictures Supporters of the Difa-e-Pakistan Council (DPC), an Islamic organisation, listen to their leaders' speeches against Burma's persecution of Rohingya Muslims, during a demonstration in Karachi Reuters/Akhtar Soomro Rohingya refugees – in pictures Hundreds of Iranians take part in a protest against violence in Myanmar after weekly Friday prayers, in Tehran EPA/Abedin Taherkenareh Rohingya refugees – in pictures Indonesian Muslim activists hold placards and shout slogans during a protest against the alleged persecution of the Rohingya minority in Magelang, Central Java, Indonesia EPA/Ali Lutfi Rohingya refugees – in pictures Members of an Islamic organisation shout slogans against the Burma government during a protest in Dhaka, Bangladesh EPA

Near his truck at the entrance to the camp, Hossain unloaded some of his goods as the lines grew around him.

“We expect these people will return home one day. For now we will help them — they are our brothers and sisters.” Then his index finger went up. “But maybe not forever.”