Although this is a very local dispute, in one way it may have the potential to cause wider problem

Gangs armed with cutlasses, bows and arrows, and locally made hunting rifles have killed and mutilated their rivals, and burned down villages.

A register kept by the state government in Benue State lists 27,000 people as having been driven from their homes.

Politically popular

This was one of the last parts of Nigeria to be brought under central government control, one of the last to be offered modern education and public services, one of the last to be influenced by either Christianity or Islam.

The present dispute, between the Jukun and the Tiv, is about land and ancient rivalries, not about religion - unlike many recent outbreaks of communal violence in Nigeria.

The latest flare-up has been made worse by the tendency in Nigeria to break down the states which make up the federation into smaller and smaller units.

This is politically popular, with even the smaller tribes and clans getting what they see as "a state of their own."

Unfortunately, all too often their first response has been to marginalise or even chase out people from other groups, no matter how long they have lived in the area.

Army recruits

But although this is a very local dispute, in one way it may have the potential to cause wider problems.

This middle belt of Nigeria has always been a major recruiting ground for the Nigerian army. Lots of soldiers come from this area - and have traditionally been valued for standing somewhat apart from the country's endemic north-south conflict.

Benue violence poses another challenge for President Obasanjo

Nigeria's current Defence Minister, retired General Theophilus Danjuma, is from one of the tribes concerned.

The recently retired Chief of Army Staff, Victor Malu, whose own village was one of those attacked, is from the other.

Even before Monday's events local people had started accusing some army units of taking sides in the conflict - a serious charge against an army which has generally maintained its reputation as Nigeria's one truly national institution.