Rhapta

Rhapta was an emporion said to be on the coast of Southeast Africa, first described in the 1st century CE. Its location has not been firmly identified, although there are a number of plausible candidate sites. The ancient Periplus of the Erythraean Sea described Rhapta as "the last emporion of Azania", two days' travel south of the Menouthias islands. The Periplus also states that the city and port were ruled by South Arabian vassals of the Himyarite kingdom, particularly a certain "Mapharitic chieftain."
According to Claudius Ptolemy, Diogenes, a merchant in the Indian trade, was blown off course from his usual route from India, and after travelling 25 days south along the coast of Africa arrived at Rhapta, located where the river of the same name enters the Indian Ocean opposite the island of Menouthias. Diogenes further describes this river as having its source near the Mountains of the Moon, near the swamp whence the Nile was said to also have its source. Ptolemy also mentions another Greek captain, called Theophilos, who took twenty days to travel from the Horn of Africa to Rhapta.
Rhapta is also mentioned by Stephanus of Byzantium and Cosmas Indicopleustes.
Stephanus of Byzantium and Ptolemy write that Rhapta was a metropolis of Barbaria.
According to Huntingford, it is certain that the people of Rhapta did not speak a Bantu language, since the 1st century AD is too early for Bantu speakers to have reached the East African coast. It is possible that the survivors of the 1st century inhabitants are the Iraqw, Gorowa, Alagwa and Burungi. Roland Anthony Oliver states that there is no evidence where Greco-Roman sources allude to the inhabitants of Rhapta being of Bantu origin.

Name

It was named Rhapta, due to the sewed boats which were used there.

Location

G.W.B. Huntingford lists five proposed locations for Rhapta:

Tanga, at the mouth of the Mkulumuzi and Sigi Rivers
Pangani, at the mouth of the Ruvu River
Msasani, three miles north of Dar es Salaam—or Dar es Salaam itself
Kisuyu
Somewhere in the Rufiji River delta, opposite Mafia Island.

Huntingford dismisses the first two as being too close to Zanzibar and Pemba islands. He observes that there is no river at Msasani, and thus concludes Kisuyu or the Rufiji delta are the most likely candidates. However, J. Innes Miller points out that Roman coins have been found on Pemba; that the Ruvu emerges near the Kilimanjaro and Meru mountains—which confirm the account of Diogenes; and that an old inscription in Semitic characters has been found near the Pangani estuary, which make Pemba a likely candidate for Rhapta. However, the first evidence of inhabitation starts solely in the seventh century at a site called Tumbe on the northern end of the island, limpidly contradicting these assertions. Furthermore, John Perkins states this: "Some Roman, Byzantine, and Sasanian coins are reported from the East African coast; however, none of these come from excavations, and the surrounding evidence suggests that they probably did not reach the Swahili Coast in antiquity. Evidence for contacts and trade between this part of Africa and the Roman and Persian worlds is mainly recorded in the limited written records."
In recent years, professor Felix Chami has found archaeological evidence for extensive Roman trade on Mafia Island and, not far away, on the mainland, near the mouth of the Rufiji River, which he dated to the first few centuries CE.

Goods

Which goods were traded at Rhapta is disputed. The Periplus only states that it was a source of ivory and tortoise shell. J. Innes Miller argues that Rhapta formed an important link in the trade route between what is now modern Indonesia and consumers in the Mediterranean region. Miller notes that ancient authorities, e.g. Herodotus state that cinnamon and cassia bark were harvested in Africa, yet these species until recently were found only in Southeast Asia, which would hint at some conflation. Miller points to the well-documented cultural links between Indonesia and East Africa. He then posits that the use of monsoons began far earlier than previously thought, allowing traders to bring their spices westward perhaps as early as the 2nd millennium BC.
It is possible that both the account of the Periplus and at least part of Miller's theory are correct, for the Periplus focuses on the availability of tortoise shell, and its silence about other goods should not be taken as evidence that other goods were not traded.