Archaeologists have unearthed dozens of clay figures in Ghana, shedding light on a sophisticated society which existed before the arrival of Islam.

Experts from the University of Ghana found 80 sculptures believed to be between 800 and 1,400 years old.

They believe the figures, depicting animal and human forms, are part of a burial ground or shrine.

Archaeologists say the societies that constructed the figures simply disappeared when Islam arrived.

"What is interesting is that the people now living in this area seem to have no connection with the makers of the figurines," said the university's Benjamin Kankpeyeng.

"That would suggest that that they have more in common with peoples living in other parts of West Africa - but we need to do more work before we can be certain."

Arab slave theory

The statues were found amid hundreds of mounds in a densely packed 30km-square area.

Mr Kankpeyeng intends to analyse the position and arrangement of the statues with Tim Insoll from the UK's Manchester University.

Mr Insoll told the BBC very little was known about civilisations in the area between 600 and 1200 AD because no written history was kept and the societies ceased to exist when Islam arrived.

He said experts still did not know why the civilisations came to an end - whether the people converted en masse to Islam, or were captured by Arab slave traders.

The statues, he said, could tell historians what kind of people inhabited West Africa in that time.

"Figures have been found in this area before, but what we can do with the latest find is map their arrangement to find out what their purpose was - whether for sacrifice or some other ritual," he said.

The northern Ghana site, near the village of Yikpabongo, was first excavated in 1985, and the dig was restarted in 2007.

The latest batch of figures was discovered in January.