MARIS GIDWELL unwinds the bandage from her forearm and removes a wooden splint. Two fingers are missing. Her arm shakes as she tells how, as dawn broke, she heard shouts warning the residents of Lawaru, in Adamawa state in north-east Nigeria, to flee. She ran towards a neighbouring village with her 25-year-old son. Tragically, men wielding machetes caught them. They robbed and wounded Ms Gidwell, and murdered her son.

The attack on Lawaru and its surrounding villages was probably carried out by nomadic Fulani herdsmen, a group that is scattered across much of west Africa’s semi-arid Sahel, from Mali to the Central African Republic. Many of those killed were sedentary farmers, mostly from the Bachama tribe. The incident is part of a growing wave of violence between nomads and farmers that has ebbed and flowed across Nigeria’s central “Middle Belt” since at least 2011.

Although strife between herdsmen and farmers dates back centuries, it has escalated sharply as climate change pushes herders south. Clashes are deadlier, too, thanks to guns looted from the arsenals of Libya’s former dictator, Muammar Qaddafi, and smuggled around the region.

The fighting is stretching a government that is also trying to contain a jihadist insurgency in the north-east and banditry in the oil-rich Niger Delta. Violence in the Middle Belt, which is about a third of Nigeria’s land mass, is every bit as brutal.

In the past year armed Fulani groups have surpassed Boko Haram, a jihadist group, as the deadliest threat to civilians. The Armed Conflict Location & Event Data Project (ACLED), a non-profit organisation, estimates that armed Fulani men have killed almost 1,000 civilians this year; Boko Haram have slaughtered 200 or so. The fighting aggravates religious tensions in a country with a perilous north-south, Muslim-Christian divide. Most Fulani herders are Muslim; most of the farmers they attack are Christian. In April two Catholic priests were killed in Benue state, along with 17 congregants. The massacre provoked national protests. “One spark could ignite a flame that no one can extinguish,” says an aid worker trying to reduce intercommunal violence. That spark may well come from the government. Ms Gidwell says that, after her village was attacked on December 4th, residents who tried to help her were fired on by a Nigerian military helicopter. The chief of a neighbouring village says his palace was destroyed in an air strike after the herdsmen had left. Amnesty International, a watchdog, says that Nigeria’s air force killed at least 35 people fleeing Fulani attacks. An air force spokesman initially claimed that only “warning shots” were fired. Later he said that a helicopter and fighter jet had returned fire at “hoodlums”. That Nigeria is using the air force to separate warring communities suggests that the police cannot cope. It would help if they sorted out their priorities. On paper Nigeria has about 300,000 police, but perhaps half of them guard the homes, offices and convoys of political bigwigs.

The general lack of security also afflicts Fulanis, who say they have taken up arms to protect themselves. Indeed, just weeks before the raid on Lawaru that injured Ms Gidwell, at least 50 unarmed Fulanis, most of them children, were killed in an attack they blamed on farmers.

Nigeria’s government is often bad at easing tensions. Some states, such as Benue, have passed laws that ban herdsmen from grazing cattle on open land. Prominent southern Christians such as Wole Soyinka, an author and Nobel laureate, think the ban does not go far enough. They want Fulani herdsmen to be declared terrorists. That would give the police greater powers to restrict their movement. Many northerners think such a ban would infuriate herders and fuel further conflict.

A more promising approach is being tried in states such as Plateau, where officials are attempting to revive and protect traditional grazing reserves and routes. Many of these date back centuries but have been encroached on by farmers as Nigeria’s population has expanded. Plateau state has also been praised for organising peace talks and mediating between hostile groups. Things do not have to fall apart. But the government needs to urge people to talk rather than reach for their guns.