Evergrande’s unraveling is still commanding global attention, but its troubles are part of a much bigger problem.

For weeks, the ailing Chinese real estate conglomerate has made headlines as investors wait to see what will happen to its enormous mountain of debt. As the slow-moving crisis unfolds, analysts are pointing to a deeper underlying issue: China’s property market is cooling off after years of oversupply.

Chinese authorities finally weighed in on the Evergrande crisis on Friday. The People’s Bank of China said the company had mismanaged its business but risks to the financial system were “controllable.”

“In recent years, the company has failed to manage its business well and to operate in accordance with market changes,” Zou Lan, director of the financial market department at the Chinese central bank, said at a press briefing. “Instead, it blindly diversified and expanded, resulting in serious deterioration of its operating and financial indicators, which eventually led to risks.”

The warning signs have been flashing for some time. Prior to Evergrande’s meltdown, tens of millions of apartments were thought to be sitting empty across the country. In recent years, the problem has only gotten worse.

Residential buildings seen in Beijing on Sept. 17, 2021. "Residential property demand in China is entering an era of sustained decline," according to one economist.

Mark Williams, chief Asia economist at Capital Economics, estimates that China still has about 30 million unsold properties, which could house 80 million people. That’s nearly the entire population of Germany.

On top of that, about 100 million properties have likely been bought but not occupied, which could accommodate roughly 260 million people, according to Capital Economics estimates. Such projects have attracted scrutiny for years, and even been dubbed China’s “ghost towns.”

Here’s a look at some of those projects, and how the problem first originated.

A worker installing safety netting at an apartment block under construction in the Nanchuan area of Xining, Qinghai province, China, on Sept. 28, 2021.

Real estate and related sectors are a massive part of China’s economy, accounting for as much as 30% of GDP. The proportion of economic output related to construction and adjacent activities is “far higher than in other major economies,” according to Williams.

For decades, that has helped the country sustain rapid economic growth.

But for years, critics have questioned whether that engine of growth was creating a ticking time bomb for the world’s second largest economy. That’s in part because of the massive debt many developers took on to finance their projects.

As China’s most indebted developer, Evergrande has become the poster child of unsustainable growth, with more than $300 billion worth of liabilities.

However, “Evergrande is not the only one struggling,” noted Christina Zhu, an economist at Moody’s Analytics. Over the last few days, a slew of other developers have disclosed their own cash flow issues, asking lenders for more time to repay them or warning of potential defaults.

In a recent report, Zhu wrote that 12 Chinese real estate firms defaulted on bond payments totaling about 19.2 billion yuan (nearly $3 billion) in the first half of the year.

“This accounted for near 20% of total corporate bond defaults in the first six months of the year, the highest across all sectors” in mainland China, she added.

The pandemic brought activity to a temporary standstill. But construction later roared back to life as China reopened, and the country’s property market enjoyed a brief rebound.

Since then, however, the market has sputtered again. And there’s no sign of immediate relief.