What is behind clashes in Ethiopia's Oromia and Somali regions?

Thousands of people have fled Ethiopia's Somali region following deadly clashes in recent days between ethnic Somalis and Oromos

The clashes have displaced at least 30,000 people, some of whom have taken refuge in makeshift camps at a stadium in the eastern city of Harar, whilst others are camping at police stations.

Local administrators have now asked aid agencies operating in the area to provide humanitarian assistance.

What is behind the conflict?

Oromia and Somali are, respectively, the two largest regions in the country by area size, sharing a border of more than 1,400 km (870 miles).

While Somalis are mostly pastoralists, living from their animals, Oromos tend to be farmers, as well as pastoralists.

Both communities inhabit the areas around the regional border.

Historically, their relationship has been characterised by territorial competition which often leads to disputes and conflicts over resources, including wells and grazing land.

These conflicts can cause the displacement of tens of thousands of people.

In 2004, a referendum to decide on the fate of more than 420 kebeles - the country's smallest administrative unit - gave 80% of them to Oromia.

Following the outcome, tens of thousands of ethnic Somalis reportedly fled the areas for fear of repercussions.

The decision has still not been implemented and this is one factor behind the current conflict.