Did Alexander the Great conquer (most of) the known world?

Owen Rees


Alexander the Great conquered most of the known world.




Alexander III of Macedon is a historical figure that attracts much hyperbole, due in no small part to what he achieved militarily in such a short space of time. By the age of 32 he had conquered the Persian Empire, entered the modern region of Afghanistan and pushed his forces southeast toward the Indus river in modern Pakistan.

There is no question that the size of his empire was phenomenal, but is it accurate to describe it as covering most of the known world?

The “known world”

Alexander’s conception of the world map was heavily influenced by Greek geographic writings such as those of Herodotus of Halicarnassus, Hecetaeus of Miletus and Ctesias, and of course from his own tutor Aristotle.

As such, he visualised the world as split into three contintents – Asia, Europe and Libya (modern Africa) – which were encircled by a large body of water: Oceanus.

Ancient Greek world map, as described by Herodotus (source).

To the west, the Greeks had already established colonies in Italy, Iberia and Gaul, giving them a good understanding of the local areas; while Herodotus tells us of Phoenician voyages that had exited the Mediterranean and circumnavigated Libya.

However, not all Greek knowledge would have had an impact on the king. Pytheas’ voyages around Britain and north toward the arctic circle (ca. 325 BCE) are unlikely to have influenced Alexander’s world view because he was in India around the same time and died shortly after, so we can not assume that Alexander was aware of all Greek exploration.

To the east, the Greeks knew about the far edges of the Persian Empire, which included northwest India. However, in characteristic style, Herodotus (4.40) in particluar admits that his information was less certain at these far edges of the world (he makes a similar point about Scythia to the north). Plutarch (Alexander 5.1) suggests that a young Alexander may have learned more from the Persians while he hosted a royal envoy, but it is difficult to know if this is apocryphal or not.

To the north, the Greeks knew about the Celts to the west and the Scythians to the east; Scythia in particular was a subject of much debate owing to its vast expanses – nobody knew how far it stretched. To the south was Libya and, at its most southern region, Aethiopia both of which the Greeks envisaged as part of their known world.

Size of his empire

Alexander’s empire was the combination of the Achaemenid empire of Persia and the extended kingdom of Macedon that he inherited from his father. Following his victory over Darius III in 331 BCE, Alexander held the lands of Macedon, Greece, Asia Minor, the Levant, Mesopotamia, parts of Arabia, Egypt and other parts of the north African coast as far as Cyreanica.

Map of the Empire of Alexander the Great (source).

His campaigns took him further east, to secure the eastern edges of the Persian empire as far as modern Afghanistan. Alexander reached the Indus river ca. 326 BCE, taking his empire to its fullest extent before turning back and returning to Babylon. Alexander never campaigned in the western half of the Mediterranean, nor did he march north against the Scythians.

During his campaign in India, according to Arrian (Anabasis, 5.26.3; transl. Pamela Mensch), Alexander warned his men of the dangers these “war-like” people still posed:

If we turn back now, many warlike races will be left unconquered between the Hyphasis and the Eastern Sea, and many others northward to the Caspian Sea, and the Scythian tribes not far beyond them.

Alexander’s empire was enormous, measuring around 2,000,000 square miles; most of which consisted of the former Achaemenid empire. However, it is quite clear that much of the known world, and the people within it, had not been conquered.


Even though Alexander’s empire did not include the whole, or even most of the known world, there is a possibility that Alexander may have claimed that he had; but, there is no ancient source which depicts Alexander making this claim. Plutarch offers an alleged quote in which Alexander actually makes the opposite point (On Tranquility of Mind 4):

Alexander wept when he heard Anaxarchus​’ discourse about an infinite number of worlds, and when his friends inquired what ailed him, “Is it not worthy of tears,” he said, “that, when the number of worlds is infinite,​ we have not yet become lords of a single one?”

There is a tradition that claims Alexander was told that the god Ammon had given him the right to rule the entire world, but it does not say he acheived this (Diodorus, 17.93.4). In fact, the only time we see such a clear assertion of Alexander’s global conquest comes from a biography, not of the Macedonian king but of Julius Caesar. In his work, Suetonius tells a version of the famous tale from when Caesar was in Spain and saw a statue of Alexander (Suetonius, Julius Caesar 7):

[S]eeing a statue of Alexander the Great in the temple of Hercules, Caesar sighed deeply, as if weary of his sluggish life, for having performed no memorable actions at an age at which Alexander had already conquered the world.

Suetonius wrote this at the turn of the second century CE, nearly 500 years after Alexander, and is focusing on Caesar, not Alexander. This is about Caesar comparing himself and failing in his eyes to live up to Alexander’s success. In this respect, the hyperbole feeds into Caesar’s imposter syndrome. A similar idea is present in Quintus Curtius, who describes Alexander’s mentality during his time in India, in contrast to his tired and battle-weary men (9.2.11):

He realised that his mind and that of his soldiers was not the same; he embraced in his thoughts the rule of the whole world and still stood at the beginning of his task, but the soldiers, exhausted by toil, now that the danger was finally at an end sought the fruit of their labour which was nearest at hand.

With regard to Alexander’s own conception of his achievements, Arrian does suggest that Alexander had plans to continue his conquests and that, if he had not died in 323 BCE, he would have headed west. This is actually a common claim in all of our source material: Alexander intended to circumnavigate Libya and bring it into his empire (Arrian, Anabasis 4.7.5, 7.1.2; Plutarch, Alexander 68.1), and one major target was Carthage (Quintus Curtius 10.1.17-19; Diodorus 18.4.4), which was a growing power in the western Mediterranean at this time.

The truth of this tradition is questionable, it appears to appeal more to the Roman audiences of these authors more than it reflects Alexander’s possible motivations, but it does highlight that there was still much of the world left to conquer.


The claim that Alexander the Great conquered the known world is a great exaggeration. His empire stretched east because he took control of the Persian empire, but he never ventured into Libya, nor did he invade western nor northern Europe, he also never took control of the Mediterranean Sea – all regions that were well known during his life time. What is more, our evidence suggests that he was well aware of this fact.

It is for these reasons that we have rated this claim false.


  • F.W. Walbank, The Hellenistic World (1992).
  • James Romm, “Alexander’s Geographic Notions”, in: J. Romm (ed.), The Landmark Arrian: The Campaigns of Alexander (2010).
  • James Romm, The Edges of the Earth in Ancient Thought: Geography, Exploration, and Fiction (1992).