Overshadowed by the fighting in Ukraine and Gaza, Sudan’s brutal civil war has been spreading for months across the western Darfur region, where atrocities were seared into international consciousness 20 years ago.

Now global attention is starting to focus on the siege of a city in Darfur, where chaotic violence has stoked fears of another ethnic slaughter, and even genocide.

Here is what we know.

A Risk of Ethnic Slaughter

The battle for the city of El Fasher, the capital of North Darfur, may have made the war too big to ignore. The U.N. Security Council, in a near-unanimous vote, has demanded an end to the siege there.

As hostile forces close in on the city, one of the biggest in Darfur, an analysis of satellite and video imagery by The New York Times has found that thousands of homes have been razed and tens of thousands of people forced to flee.

The fighters are part of a paramilitary group known as the Rapid Support Forces. Given their history — they are successors to the janjaweed militias that once brutalized civilians — and accounts of a massacre in another city last fall, many fear the worst.