Alexander the Great, artistic reconstruction by the author.
However, in the 21st century, its unlikely that any individual interested in history and geography would be unaware that the region extending from the Indus to the Ganges and spanning towards Bengal has always been recognized as one of the most densely populated areas on the planet. As early as ancient times, there were robust states, affluent cities, and sophisticated farming practices. These lands were among the first to be settled by the Aryans, who had arrived here over 1,000 years prior to the accounts documented by ancient writers. In Alexanders era, they were the quintessential hub of our civilization. The only obstacle standing in his way was the idea of scouring the vast territory of Africa for the scattered primitive tribes eluding his pursuit.
Alexander on the shores of the External Sea (Atlantic Ocean). Artistic reconstruction by the author.
If we restore the geography that was turned upside down in the 19th century to its correct position, the events will fall into logical order. When Alexanders army conquered the Persian Empire from Indias territories, all satrapies of the empire came under Alexanders rule, including almost all of East Africa, which by that time was already well known and explored. The few rebellious regions of the empire that he defeated were conquered easily enough in a few swift campaigns. There were still little-known territories in Central and Southern Africa that were under the notional control of the Persian Empire, although nominally recorded and accounted for as the lands of the Persian Emperor. Although the Persian Empire very tentatively controlled these territories, there was really nothing to control due to the remoteness, lack of infrastructure, and economic unlivability of these territories at the time. Nevertheless, Alexander, of course, had to see it for himself and was not satisfied with the stories of former advisers of the Persian Emperor.
The Route of Alexander the Greats Fleet Around North Africa. Authors map from his archive.
The journey from the banks of the Nile to the Niger (these are the modern names of these rivers, in ancient times they were called Euphrates and Indus respectively) along the southern border of the Sahara was not marked by great battles, but rather by an expeditionary military campaign with small skirmishes, relatively easy victories and the swearing in of local kings and chiefs. In some cases Alexander appointed new leaders from among his trusted military personnel, in others he retained those who had already submitted.
In contemporary historical works, this expedition is referred to as Alexanders Campaign from the Euphrates to the Indus. A flotilla was built on the banks of the Niger (the historical Indus), which descended into the Atlantic Ocean (this ocean was called the «Outer Sea» in the ancient times).
Alexander the Great is at the «edge of the earth» on the coast of the «Outer Sea» (Atlantic Ocean). Artistic reconstruction by the author.
A detachment of the army was sent westward along the coast to pacify all the monarchs and leaders throughout the territory from the Sahara Desert to the Gulf of Guinea, which was successfully accomplished. Later the fleet made an independent campaign to the north along the coast of West Africa to the Mediterranean Sea. Alexander personally led the main army from the mouth of the Niger to the Congo River.