Between the first century BC and the fourth century AD, several expeditions and explorations to Lake Chad and western Africa were conducted by groups of military and commercial units of Romans who moved across the Sahara and into the interior of Africa and its coast. The primary motivation for the expeditions was to secure sources of gold and spices.
Characteristics
The Romans organized expeditions to cross the Sahara along five different routes:
All these expeditions were supported by legionaries and had mainly a commercial purpose. Only the one conducted by emperor Nero seemed to be a preparative for the conquest of Ethiopia or Nubia; in 62 AD, two legionaries explored the sources of the Nile. One of the main objectives of the explorations was to locate and obtain gold, using camels to transport it overland back to Roman provinces on the Mediterranean coast. The explorations near the coasts were supported by Roman ships and deeply related to overseas commerce.
Main explorations
The Romans conducted five main explorations: two in the western Sahara, two in the central Sahara, and one in the area of Lake Chad.
Western Sahara expeditions
In western Sahara there were two Roman expeditions, just south of the Atlas mountains:
Cornelius Balbus expedition: The first expedition done by Romans in the Sahara—according to Pliny—was the one of Cornelius Balbus, who in 19 BC probably reached the riverNiger near Timbouctou. He moved from Libyan Sabratha and conquered with ten thousand legionaries the Garamantes capital in Fezzan and sent a small group of his legionaries further south across the Ahaggar mountains in order to explore the "land of the lions": they found a huge river that in their opinion was going toward the Nile river. Indeed in 1955, many Roman coins and some Latin ceramics were found in the area of Mali.
Suetonius Paulinus expedition: The second was done in the year 41 AD by Suetonius Paulinus, a Roman Consul, who was the first of the Romans who led an army across the Atlas range. At the end of ten days' march he reached the mountains summit covered by snow and later he arrived at a river called Gerj. He then penetrated into the semi deserted country south of Morocco and some of his legionaries probably went near the river Daras.
From the first century AD there is evidence of Roman commerce and contacts in Akjoujt and Tamkartkart near Tichit in Mauritania.
Central Sahara expeditions
The two main explorations/expeditions in the central Sahara were:
Flaccus expedition: During Augustus times Lake Chad was a huge lake and two Roman expeditions were carried out in order to reach it: Septimius Flaccus and Julius Maternus reached the "lake of hippopotamus". They moved from coastal Tripolitania and passed near the Tibesti mountains. Both did their expeditions through the Garamantes' territories, and were able to leave a small garrison on the "lake of hippopotamus and rhinoceros" after 3 months of travel in desert lands.
Ptolemy wrote that in 50 AD Septimius Flaccus carried out his expedition in order to retaliate against nomad raiders who attacked Leptis Magna, and reached Sebha and the territory of Aozou. He then reached the rivers Bahr Erguig, Chari and Logone in the lake Chad area, described as the "land of Ethiopes" and called Agisymba.
Matiernus expedition: Ptolemy wrote that around 90 AD Julius Maternus carried out a mainly commercial expedition. From the Sirte gulf he reached the Oasis of Cufra and the Oasis of Archei, then arrived -after 4 months travelling with the king of the Garamantes- to the river Bahr Salamat and Bahr Aouk, near modern-day Central African Republic in a region then called Agisymba. He went back to Rome with a rhinoceros with two horns, that was shown in the Colosseum.
According to Raffael Joorde, Maternus was a diplomat who explored with the king of Garamantes the territory south of the Tibesti mountains, while this king executed a military campaign against rebellious subjects or as a "razzia".
Niger river area
However some historians believe that there was even another Roman expedition to sub-saharan central Africa: the one of Valerius Festus, that could have reached the equatorial Africa thanks to the Niger river.
Festus expedition: Pliny wrote that in 70 AD a legatus of the Legio III Augusta named Festus repeated the Balbus expedition toward the Niger river. He went to the eastern Hoggar Mountains and the entered the Air Mountains as far as the Gadoufaoua plain. Gadoufaoua. Festus finally arrived in the area in which Timbuktu is now located. Some academics, such as Fage, think that he only reached the Ghat region in southern Libya, near the border with southern Algeria and Niger. However, it is possible that a few of his legionaries reached as far as the Niger river and went down to the equatorial forests navigating the river to the estuary in what is now Nigeria. Indeed something similar happened in the Nile river exploration done under Nero emperor in Uganda.
Maritime explorations
The Roman vassal king Juba II organized successful trade from the area of Volubilis. Pliny the Elder, who was not only an author but also a military officer, drawing upon the accounts of Juba II, king of Mauretania in the first century AD. Pliny stated that a Roman expedition from Mauritania visited the islands of the archipelago of the Canaries and Madeira around 10 AD and found great ruins but no population, only dogs. According to Pliny the Elder, an expedition of Mauretanians sent by Juba II to the archipelago visited the islands: when King Juba II dispatched a contingent to re-open the dye production facility at Mogador in the early 1st century AD, Juba's naval force was subsequently sent to explore the Canary Islands, Madeira and probably the Cape Verde islands, using Mogador as their base. According to Pliny, the Greek Xenophon of Lampsacus stated that the "Gorgades" were situated two days from "Hesperu Ceras", the westernmost part of the African continent, showing a knowledge of the area by the Romans. Furthermore, according to Pliny the Elder and his citation by Gaius Julius Solinus, the sea voyaging time crossing from the Gorgades to the islands of the Ladies of the West was around 40 days: this fact has prompted academic discussions about the possibility of further Roman travels toward Guinea and even the Gulf of Guinea. A Roman coin of the emperor Trajan has been found in Congo. Other Roman coins have been found in Nigeria and Niger, and also in Guinea, Togo and Ghana. However, it is much more likely that all these coins were introduced at a much later date than that there was direct Roman intercourse so far down the western coast. No single article unmistakably originating in Africa south of the Equator has been discovered in the Graeco-Roman world or in contemporary Arabia, nor is there any mention of such an article in written records: while the coins are the only ancient European or Arabian articles that have been found in the central parts of Africa. Emperor Augustus decided that the circumnavigation of Africa should also be attempted. The Romans had two naval outposts in the Atlantic coast of Africa: Sala Colonia near present Rabat and Mogador in southern Morocco. The island of Mogador prospered from the local purple dye-making industry from the reigns of Augustus until Septimius Severus. Augustus, based on the discovery of a sunken merchant ship from southern Hispania in the Djibouti area, wanted to organize an expedition from Egypt to Mogador and Sala around Africa, but it seems that it never took place.