South Sudan's crisis, which has left perhaps 1,000 people dead and 200,000 displaced since fighting began in mid-December, is about much more than just ethnicity. It's about political infighting, about corruption, about weak and divided government institutions.

Still, ethnicity is a real and significant factor in the crisis. Communal violence is rising between Dinka and Nuer, the country's two largest ethnic groups. That's exacerbating the flight of many civilians into camps for refugees and internally displaced persons. The BBC's Alastair Leithead, visiting a U.N.-run camp near the South Sudanese town of Bentiu, found a sign that captures these two intersecting problems remarkably well. It's at 2:22 and shows signs directing camp arrivals one way if they're Dinka and another if they're Nuer.

Here's a screenshot of the sign:

Screenshot from BBC video showing a sign directing new arrivals at a displaced persons camp to divide by ethnicity. (YouTube)

There are two reasons this is significant. First, apparently the people running the camp are under the impression that the tensions between Dinka and Nuer have gotten bad enough that even fleeing civilians need to be separated. The sign could represent a response to fighting between some of the displaced and be intended to preempt any possible further conflicts. Or maybe the new arrivals want to be separated by ethnicity because they feel safer that way. One man told the BBC's Leithead that his family had been attacked by armed men simply for speaking the Dinka language. As NPR's Gregory Warner reported from the country last week, "People are starting to ask who their neighbors are."

The second reason this is significant is because it could, some South Sudan-watchers warn, actually reinforce ethnic divisions. In South Sudan, lots of people just want to avoid the fighting and live in peace, alongside people of other ethnic groups. And, as I noted above, it's not all about ethnicity. This sign could send the message, however unintentionally, that all Dinka and Nuer are party to the conflict, whether they want to be or not -- that they should voluntarily self-segregate rather than coexist. As Sudan scholar Bec Hamilton writes, "There are plenty enough unscrupulous Southern Sudanese elites right now who are fueling the ethnic flames for their personal gain, without the UN putting its stamp of approval on it." She adds, "We need to remember that this started as a political conflict and the actions of people who have a choice -- like the UN -- matter in terms of the direction it goes from here."

This is not to bash the United Nations. Running an internally displaced persons camp in the middle of a conflict zone, one where the fighting can have ethnic overtones, has got to be extremely difficult. It's just to point out how delicate ethnic tensions can be. They can have their own, self-sustaining logic, in which the fear or perception of ethnic conflict can make actual fighting more likely as people start looking at their neighbors as possible threats or start reverting from a national identity to an ethnic one. There's nothing that makes Dinka and Nuer necessarily unable to peacefully coexist; Hamilton is right that some bad actors in South Sudan are trying to stir up ethnic tensions out of self-interest. The irony is that the tensions are so sensitive that even groups who clearly want only to help could unintentionally reinforce them. The fact that one well-intentioned sign at a displaced persons camp could be cause for legitimate concern shows just how serious this crisis is getting.