Prof Chami work
Tanzanian dig unearths ancient secret
The remains hold clues about Africa's ancient history
Off Mafia Island, Tanzania
A discovery which a Tanzanian archaeologist believes will change how East African history is regarded has been made on tiny Juani Island, off the Tanzanian coast.
These discoveries show the people here were interacting with other civilisations - and long before the Islamic era
Prof. Felix Chami
Felix Chami, professor of archaeology at the University of Dar es Salaam has uncovered a major site on Juani, near Mafia Island, which he believes will substantially increase the evidence that East Africa was part of a wider Indian Ocean community.
Previous to Dr Chami's other discoveries on the Tanzanian coast, scholars had never considered East Africa as part of the ancient world.
The professor had been alerted to the existence of the cave by two local men who informed Peter Byrne, owner of a small lodge on Mafia Island and supporter of efforts to discover the intriguing history of these small islands - which are now entirely dependent on fishing.
We sailed on a dhow from Mafia Island to a beach on nearby Juani Island which Dr Chami believes may have been an ancient port since the Iron Age.
Juani island has lush vegetation
Unlike the other islands, Juani has fresh water and soil suitable for agriculture.
The two local men, whose curiosity had overcome beliefs that the caves are inhabited by spirits, led us more than a kilometre along jungle tracks.
The men hacked a path through the luxuriant growth with pangas which revealed a collapsed coral cave around 20 metres in diameter.
With the help of hanging vines we climbed down into the cave.
Scattered throughout the seven to 10-metre-high overhanging cave were shards of pottery, human bones and three skulls.
Dr Chami examined the skulls but said only carbon dating would establish their age.
He was most excited by the large habitable area of soft loose soil, at least 50 square metres.
"There could be three metres of layers here to establish a cultural chronology," he says.
"This is a marvel. I believe this was a major Iron Age site. I can assure you this will change the archaeology of East Africa."
Felix Chami will return to the site with his team after the rainy season to start a full excavation.
In the past five years Dr Chami has overturned the belief that Swahili civilisation was simply the result of Indian Ocean trade networks.
"It was thought that Swahili settlements were founded by foreigners, particularly by Islamic traders," he says. "But these discoveries show the people here were interacting with other civilisations - and long before the Islamic era."
Dr Chami believes the coastal communities may have been trading animal goods, such as ivory as well as iron.
Professor Chami got inspiration from Ptolemy
Dr. Chami utilised the writings of Greek geographer Ptolemy (c.87-150 AD) who described settlements in East Africa as "metropolis" and also referred to "cave dwellers".
Ptolemy even specified a latitude eight degrees south on a large river -the location of the Rufiji river.
It was there on the hills above the river that Dr Chami found the remains of settlements with ancient trading goods and evidence of agriculture.
Directly opposite the Rufiji delta are Mafia & Juani Islands.
Dr Chami's excavations uncovered cultural artefacts which have been carbon dated to 600 BC.
They included Greco-Roman pottery, Syrian glass vessels, Sassanian pottery from Persia and glass beads.
But Felix Chami believes the new site on Juani Island may well be the most significant yet.