When heavily armed rebels in northern Mali forced government troops into a hasty retreat two months ago, Hama Baye knew it was time to leave. ''If even the army is running away from them what do you think a common citizen can do?'' the herdsman says. ''We are helpless and afraid so we ran away too.''
Hama, his wife Saouda and their children have been sheltering in a tiny makeshift hut on baking sand at Mangaize in Niger ever since. They're among 45,000 Malians who have taken refuge in Niger, even though food shortages in that country threaten nearly half its population. The United Nations says almost 320,000 Malians have fled their homes and expects to help about 440,000 displaced people inside and outside the country this year.
Sahel's vunerable women
Herald photographer Janie Barrett looks at Sahel's vulnerable women
The convergence of tribal rebellion, jihadist ideology, drought, weak governance and an influx of heavy weapons has crippled Mali and dangerously destabilised the whole Sahel region across West Africa.
The grim conditions at Mangaize refugee camp are emblematic of the misery.
Plan, an aid agency providing assistance to the refugees, says 27 per cent of those aged under five in the camp are malnourished and 38 per cent of pregnant and nursing mothers are malnourished. Tragedy struck Hama Baye's family two weeks ago when their two-year-old boy, Moussa, fell ill and died. ''We buried him there in the bushes,'' says Saouda as she gestures to the sandy scrub that lies beyond her lean-to. Another one of her children is being treated for malnutrition.
Until a few months ago, Mali was considered one of Africa's most successful democracies and its descent into political chaos has caught many by surprise.
The triumphant rebels - an alliance of heavily armed Tuareg tribesmen and radical Islamic groups - now control a vast tract of northern of Mali.
A group representing disaffected members of the Tuareg tribe - the National Movement for the Liberation of Azawad (MNLA) has declared an independent homeland in northern Mali. Al-Qaeda in the Islamic Maghreb (AQIM) and Ansar Dine - both groups linked to al-Qaeda - are involved in the rebellion. Ansar Dine has already begun to impose sharia in the ancient town of Timbuktu.
There are fears Islamist groups in northern Mali have ties to Boko Haram, an extremist group responsible for a spate of violent attacks in northern Nigeria, and there are unconfirmed reports that fighters from Algeria, Afghanistan and Pakistan are operating in northern Mali.
The success of the rebels triggered a military coup in Mali two months ago and the government - which now only controls the south of the country - has been paralysed by confusion and infighting. Local analysts and aid workers believe the international community is not paying sufficient attention to developments in the Sahel, one of the world's most fragile regions.
Professor Mahaman Tidjani Alou, a political scientist at Niger's Abdou Moumouni University, says the Sahel has become a ''very dangerous zone'' that poses a threat well beyond the region. ''We know the environment in West Africa is now very unstable and if it continues, the security of Europe, and the world, will be threatened in the end,'' he told the Herald. ''But it's our impression that the world is keeping quiet and letting all these things keep going. It is very tragic.''
The war in Libya that ousted Muammar Gaddafi triggered the unexpected crisis in Mali.
''It's all a chain of events,'' says Rheal Drisdelle, who has worked in the Sahel region for 25 years and is the Niger country director of aid agency Plan.
''The Tuareg rebels in Mali were mercenaries who worked for Colonel Gaddafi in Libya. So when France, the UK and other European powers bombed Gaddafi into oblivion these mercenaries returned to Mali extremely well armed. They set themselves up in northern Mali where these Islamist groups already were.''
French analyst Roland Marchal says the aftermath of the Libyan crisis ''created a new and potentially destabilising variable in the form of thousands of disenfranchised soldiers who are both well equipped and uncertain of their status.''
But the armed outfits that combined to drive government troops out of northern Mali - including the secular MNLA and Islamist groups - do not have a common agenda.
There are reports that fighters have occupied different parts of each city and sometimes compete for whose flag should fly over key buildings.
''What is unclear is whether they will be able to co-exist on the same territory while trafficking and a protection economy are the only sustainable resources,'' Marchal wrote in a report on Mali conflict published last month by the Norwegian Peacebuilding Resource Centre.
Divisions are already appearing among the rebels. An agreement reached last week by the Tuareg MNLA and the Islamist Ansar Dine to create a new Islamic state appeared to collapse two days later over the imposition of sharia.
There are fears Mali's conflict will spread into neighbouring Niger which has a significant Tuareg population. Tuareg insurgents in the region have long demanded a homeland - called Azawad - which stretches across several countries including parts of Mali and Niger.
There is also concern in Niger about the influence of Nigerian militant group Boko Haram along its southern border.
''We are doing everything so that it doesn't influence or contaminate our population,'' Djibo Tinni, a senior government official in Niger's Diffa district, says. ''The government is making every effort in terms of military surveillance and awareness raising.''
Meanwhile, a deepening food crisis threatens 18 million people across the region including 3.5 million in Mali and 6.4 million in Niger. At the eastern end of the Sahel region, tensions simmer between Sudan and South Sudan. The bitter rivals stepped back from all-out war after a series of bloody border clashes last month but emergency peace talks in Ethiopia have not yet been conclusive.
''I've been living and working in the Sahel for 25 years and I have never seen a situation like what we are going through right now, it is extremely fragile,'' Drisdelle says. ''It's a very worrying time in the Sahel and its taking place amid food insecurity, high malnutrition rates and refugees.
''It's a perfect storm scenario and it's quite frightening.''
Guido Cornale, a veteran UN official, who has worked in Mali and is now the UN's humanitarian co-ordinator in Niger, says the security situation in the Sahel threatens to hamper the delivery of much-needed humanitarian assistance.
''If the situation in Mali is not responded to very soon there is a severe risk of instability all across the Sahara and the Sahel regions,'' he says. ''That will create a major problem in delivering humanitarian assistance, for development programs and all the rest.
''You can imagine the 'Somalia-isation' of the Sahel in which you get a rebellion growing, Islamists coming from the south and the north and the situation spinning out of control … this is the worst-case scenario one can imagine but the situation in Mali is pretty worrisome.''
Drisdelle fears the international community is only paying ''lip service'' to Sahel's deep-seated problems, especially the growing influence of religious extremists. He warns the multiple crises in the Sahel have the potential to cause instability across western and northern Africa and even Europe. ''This is not to be taken lightly,'' he says. ''It could have repercussions all across Europe and North America.''
Matt Wade and photographer Janie Barrett were supported by CARE Australia, Plan International Australia and Save the Children Australia to report from West Africa.