GAZA CITY — In the Forgotten Neighborhood, houses have walls but no floors: people sit, eat and sleep on the sand.

One resident, Maliha Hjila, is not sending her 14-year-old twin daughters to school this year because she has no money for books or backpacks. Sameer Malaka’s 7-year-old son, Saqer, started first grade last week, but without a new shirt, pants or shoes. “There is no word to describe how difficult it is when your kid asks for something and you can’t,” said Mr. Malaka, who has not worked for years.

During Ramadan last month, several neighborhood families slaughtered a lame horse and used its meat for kebabs because they could not afford beef or lamb; some mornings, Reem al-Ghora did not wake her daughters for the predawn, prefast meal, she said, “because there was no food.”

A report issued Aug. 27 by the United Nations mission in Gaza questioned whether the 139-square-mile area will be “a livable place” in 2020, citing shortages of food, water, electricity, jobs, hospital beds and classrooms amid an exploding population in what is already one of the most densely populated patches of the planet. But for thousands of Gaza’s poorest residents, like those who live in the forlorn crop of cinder-block or rusted-zinc shacks built illegally on government land and known as the Forgotten Neighborhood, “It’s unlivable before then — even today,” as Ms. Hjila put it.