The killing of five foreign tourists in north-west Ethiopia has again drawn international attention to one of the most remote and lawless parts of the world.
Four other people were kidnapped in the incident in the mostly desert Afar region, where there have been periodic attacks on foreigners blamed on rebel groups.
In 2004, a French tourist disappeared in the region, reportedly leaving "no trace but her rucksack", and in 2007, a group of European nationals were kidnapped in Afar, but later released by the separatist rebel group that captured them.
As in previous cases, Ethiopian officials have blamed the most recent attack attack on militant groups funded and trained by the Eritrean government, which denies any involvement.
Who are the Afars?
About 1.4 million Afars live in Ethiopia with smaller, but still very significant, Afar communities living as minorities in the neighbouring countries of Eritrea and Djibouti.
Most Afars are nomadic herders. Some also trade in the salt that can be mined from the Danakil Depression, a very hot and barren area lying below sea level and straddling the Eritrea-Ethiopia border.
The Afars have their own language, Afar. Almost all of them are Sunni Muslims.
Famed as the hottest place on Earth, the geological depression of salt lakes in Afar is home to the active Erta Ale volcano - an attraction to adventure tourists.
The region is also known for frequent non-political banditry and therefore the Ethiopian government requires tourists visiting the area to be accompanied by a police escort.
Further danger arises from the area's proximity to the border between Ethiopia and Eritrea who fought a fierce two-year war in 1998. In February 2008, "elements backed by the Eritrean government" infiltrated the area and attempted to kidnap 28 tourists, mostly of French nationality, Ethiopian television ETV reported.
Although a cease-fire between Ethiopia and Eritrea is in place, it remains fragile and a permanent settlement to the border dispute continues to be elusive. Both sides maintain a hostile media campaign against each other.
A number of rebel groups however operate in Afar. The most prominent of these are the Afar Revolutionary Democratic Unity Front (ARDUF), which has been active for more than a decade.
It was founded in 1993, bringing together three existing Afar organisations. It kidnapped some Italian tourists in 1995, later releasing them unharmed. An earlier rebel group, the Afar Liberation Front (ALF), fought against the then-communist government of Ethiopia between 1975 and 1991. The ALF later continued to lobby for Afar interests but not through military means.
Another, separate, Afar insurgency was mounted in 1991 to 1994 in neighbouring Djibouti by the Front for the Restoration of Unity and Democracy (FRUD). A splinter faction continued to fight until 2000.
Also operating in the region is the Red Sea Afar Democratic Organisation, an Eritrean rebel group.
The ARDUF seeks the creation of an independent Afar homeland, which would include areas of Ethiopia, Eritrea and Djibouti.
There is disagreement on whether this would be an internationally recognised sovereign state or an autonomous region within Ethiopia. The group has always been very firm, however, in opposing the existence of the separate state of Eritrea, as the creation of that country split the Afar homeland.
In Eritrea, Afars dominate the south-east of the country, including the Red Sea port of Assab. One of the ARDUF's slogans is "The Red Sea belongs to the Afars".
During the 1998 Ethiopia-Eritrea border war, the ARDUF took Ethiopia's side and declared a cease-fire in operations against Ethiopian forces.
In 2002, one faction of the ARDUF went even further in its reconciliation with Addis Ababa and declared that it would permanently abandon armed struggle in favour of peaceful involvement in Ethiopian politics.
But a rival faction denounced this move, declaring that ARDUF leader Mohamooda Ahmed Gaas had been expelled for treasonable activities and vowed to continue the secessionist campaign by military means.
However, the intensity of the ARDUF's military operations in recent years does appear to have been weakened by these internal disagreements. At most, it has been conducting a rather low-level insurgency.
In March 2011, the armed ARDUF faction claimed to have killed 49 government soldiers in the area.
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