AL HOL, Syria — No one thought baby Ibrahim was going to make it.

The 18-month-old boy, Belgian by birth, was malnourished, dehydrated, and vomiting every half an hour from a stomach bug. In Al Hol, the refugee camp in northeast Syria where he was staying, the heat regularly reached a relentless 100 degrees by midmorning, there was scant medical care, and fresh water, when it arrived, usually teemed with bacteria. Video of Ibrahim, listless and throwing up, had made its way from this desolate desert patch of Syria to his aunts in Belgium, who had shared it with doctors there. “I’m going to be honest, this baby is going to die,” one said. Another thought it would only be a matter of hours. A Belgian mission to rescue and repatriate orphan children arrived in the camp in June and made Ibrahim their top priority. But Ibrahim did not appear on the camp officials’ prisoner list. No one had heard of him. What had happened to the baby on verge of death?

The camp where the footage was taken, Al Hol, holds 73,000, mostly women and children formerly associated with ISIS, living together under squalid tents, lacking access to basic sanitation, clean water or food supplies. As of July, at least 240 children had died either in the camp or en route. The week I visited early this summer, a 4-year-old boy drowned after tumbling into a fecal pit. A few weeks before that, a 7-year-old burned to death in a tent. All his family back home received was a photograph of his charred body. The still-healthy ones run feral within the camp’s confines.

Al Hol, originally built in the early 1990s to house Iraqis fleeing the first Gulf war, is called many things these days, among them “the camp of death,” “a test from God,” “a mini-ISIS caliphate,” and “Guantánamo in the desert.” Most of its inhabitants arrived early this year, escaping the fighting around Baghouz, ISIS’ last stronghold; during the most intense period, around 10,000 women and children arrived on a single day. These included the Islamic State’s most devoted adherents — those who were willing to eat weeds and sleep under trees until the group lost its final sliver of territory.

The foreign-born children in the camp number nearly 8,000. They were either taken by their parents to Syria or born there of the serial mandatory matches between fighters and muhajirat, or migrant women, that became the Islamic State’s chief recruiting lure and its most cruel imposition on women.

Today these children are lost — sometimes literally. They are currently growing up among women who would see them as the next generation of jihadists in waiting. Children of some nations, particularly Russia, Turkey and some Central Asian republics, have gone home more quickly, but Western children have not fared as well. Some have been abandoned by the countries where they are ostensibly citizens. Others can’t be tracked down, even by countries that would take them in. Their prospects of returning to the West soon look bleak, but what everyone believes, quietly, is that many will make it back eventually.

I visited Al Hol in late June to interview women in the camp, hoping to gain a measure of those detained, their commitment to jihadism, and what risks they might pose to their home countries, as well to other women and children living alongside them. I came away wondering about the fraying, endangered notion of citizenship, and what it really means to be a citizen of a Western democracy, when a combination of fear and political expedience has resulted in the abandonment of thousands of children to this sprawling ISIS prison in the desert.