Introduction
For many years, critics of the Quran have focused on just one part of the Dhul-Qarnayn story (Quran 18:83–101): the sun setting into a muddy spring. It is scientifically impossible for a giant star to sink into a small pool of mud on Earth. However, this heavy focus on "the mud" has caused critics to miss a much bigger scientific problem in the same story.
The truly missing criticism in modern debates is not about where the sun sets, but how close the sun gets to the edges of a flat Earth.
When we read the Quran and its earliest, most trusted commentaries, we see a clear picture of an ancient flat-earth model. The real scientific crisis is how the Quran describes both the Western and Eastern edges of the world. In the mind of the author, traveling to the ends of the Earth meant physically getting closer to the sun's low path. Because of this, both the western pool and the eastern lands are described as extremely hot places because they are physically too close to the sun.
On our round Earth, the sun is 150 million kilometers away. Every place on the globe is basically the same distance from the sun. No geographic "edge" is closer to the sun than any other. But the Quran's physics assumes a flat surface where the sun drops down so low that it boils the western water and burns the eastern people. This article looks at this forgotten error in the Quran, showing that early Muslims did not view these verses as metaphors, but as literal flat-earth physics.
The Quranic Western Edge: The Sun Sets in a Spring of Hot Water
The story of Dhul-Qarnayn shows that the Quran uses a flat-earth model. The text says he traveled to the western and eastern edges of the Earth. At these edges, he found extreme heat caused by the sun being too close. This only makes sense if the sun moves across a flat surface at a very low height. It does not make sense on a round Earth.
Quran 18:86 states:
حَتَّىٰٓ إِذَا بَلَغَ مَغْرِبَ ٱلشَّمْسِ وَجَدَهَا تَغْرُبُ فِى عَيْنٍ حَمِئَةٍ
Until, when he reached the setting place of the sun, he found it setting in a spring of hot water (or dark mud).
The greatest early commentator, Imam Ibn Jarir al-Tabari (died 923 CE), explained the words "hot water" (ḥāmiyah) and "dark mud" (ḥami'ah). He said the spring was both things at the same time. In his famous book Tafsir al-Tabari, he wrote under the commentary of verse 18:86:
"The correct view... is that it was a spring that was both hot and muddy at the same time..."
Centuries later, the famous scholar Ibn Kathir (died 1373 CE) repeated this same physical explanation. Even though some Muslim scholars in his era had started to accept that the Earth is round, the early text forced him to repeat the old flat-earth physics under verse 18:86:
تَغْرُبُ فِي عَيْنٍ حَامِيَةٍ، يَعْنِي: حَارَّةٍ قُلْتُ: وَلَا مُنَافَاةَ بَيْنَ مَعْنَيَيْهِمَا، إِذْ قَدْ تَكُونُ حَارَّةً لِمُجَاوَرَتِهَا وَهَجَ الشَّمْسِ عِنْدَ غُرُوبِهَا، وَمُلَاقَاتِهَا الشُّعَاعَ بِلَا حَائِلٍ
"Ibn Jarir said, 'There are two well-known recitations... and whichever one the reciter recites is correct.' And I say, there is no contradiction between their two meanings, as the water may be hot because it is near the glare of the sun at sunset, and it meets the rays without any barrier."
Notice what Ibn Kathir is saying. They are not talking about a local volcanic hot spring or a mirage. They are giving a physical reason for why the water is hot: it is hot because it is physically close to the literal place where the sun sets.
On a round Earth, no place is closer to the sunset than any other. The idea that you can travel to a "setting place" where the water is boiling from solar proximity only works on a flat plane where the sun physically drops down to a reachable spot.
The Quranic Eastern Edge: The Sun Rises on a People Scorched by Proximity
The Quran shows the exact same picture at the opposite edge of the world. Verse 18:90 states:
حَتَّىٰٓ إِذَا بَلَغَ مَطْلِعَ ٱلشَّمْسِ وَجَدَهَا تَطْلُعُ عَلَىٰ قَوْمٍ لَّمْ نَجْعَل لَّهُم مِّن دُونِهَا سِتْرًا
Until, when he came to the rising place of the sun, he found it rising on a people for whom We had provided no shelter against it.
In his commentary, Imam Al-Tabari shares reports from the very first generations of Muslims to explain this verse. He shares the words of an early scholar named Qatadah, who described the extreme heat at this eastern boundary: (link):
"It was mentioned to us that they were in a land where nothing grew (because of the heat). When the sun rose, the people would go into underground tunnels until the sun passed the middle of the sky. Then they would come out to live their daily lives. Once an army came to them, and the locals said, 'You should not be here when the sun rises.' But the army said, 'We will not leave until the sun rises. But what are these bones lying here?' The locals replied, 'These are the bones of an army that came before you. The sun rose on them here, and they died.'"
Al-Tabari records another early narration from Jahdam (جَهْضَم). He stated that the land is so close to the rising sun that people cannot build houses or grow food, and the sun burns them every day.
The critical detail here is that Qatadah and the other early sources are not describing a normal hot desert. They say this deadly heat is caused by being physically close to the literal place where the sun rises. In this worldview, the eastern edge of the Earth is unlivable for the exact same reason the western edge is. In a flat-earth model, these boundaries are the closest points to the sun's low orbit.
The Failure of Modern Apologetics
Modern Muslim apologists often argue that these verses only describe what Dhul-Qarnayn saw from his personal perspective. They claim it was just a mirage, a local hot spring, or a standard desert sunrise.
But this modern explanation completely contradicts the classical commentators. Neither Al-Tabari nor his early sources treat the boiling water or the burned people as optical illusions, metaphors, or normal weather. Instead, they use literal, flat-earth physics to explain the intense heat:
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No Barrier: They explicitly state that the western water was heated by the glare of the sun because there was no barrier between them.
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Tunnel Survival: They describe a civilization living in tunnels just to escape being burned to death by the rising sun. If the Quran just meant a normal sunrise, it makes no sense for early Muslims to tell a story where armies turn into skeletons simply by standing outside in the morning.
Together, these verses and their early explanations show a consistent model. The Earth is seen as a flat plane with edges that sit dangerously close to the sun's physical path. This is not a poetic exaggeration; it is the core premise of the whole story. It proves that a flat-earth cosmology was the exact model present in Muhammad's mind.
The Closeness of the Sun to the Edges of the Earth in Ancient Greek and Roman Works
In ancient classical worldviews, the Earth was frequently envisioned as a flat disc or plane. Writers explicitly attributed the extreme heat at the world's extremities to the sun's physical closeness to those edges.
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Herodotus (5th Century BCE): In his Histories (Book 3, Chapter 104), the Greek historian Herodotus noted that in India, which he believed was the far eastern edge of the world, the sun in the morning was incredibly close to the inhabitants. He wrote: "Now in these parts the sun is hottest in the morning, not at midday as elsewhere, but from sunrise to the hour of market-closing (LacusCurtius.Herodutus, Book 3, Chapters 89-111)." And also: "Now among these nations the sun is hottest in the morning hours, not at midday as with others, but from sunrise to the time of closing the market: and during this time it produces much greater heat than at midday in Hellas, so that it is said that then they drench themselves with water (The History of Herodutus, vol. 1)."
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Pliny the Elder (1st Century CE): In his foundational work Natural History (Book 2, Chapter 80), Pliny explained that global traits are determined by a region's literal distance from the sun. He asserted: "There can be no doubt, that the Ethiopians (in the south, below Egypt, sub-Saharan Africa and Nubia ) are scorched by their vicinity to the sun's heat." And he also wrote: "For it is beyond question that the Ethiopians are burnt by the heat of the heavenly body near them, and are born with a scorched appearance (Pliny, Natural History, Section 176-248). " Conversely, those in the extreme North have white skin and yellow hair because their climate is frosty due to their great distance from the sun. This shows that in the ancient worldview, travelling to the far boundaries of the world meant physically approaching the sun's actual path. The text is accessible through the Natural History by Pliny the Elder on Perseus Digital Library.
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Strabo (1st Century CE): In Geography (Book 1, Chapter 2, Section 24), Strabo quotes and defends the older cosmological descriptions of the extreme edges of the world. Discussing why the inhabitants at the furthest boundaries of the known earth are scorched, he quotes the ancient geographic consensus:
"The (eastern and western) Ethiopians are divided into two groups, the ones towards the rising sun, and the others towards the setting sun... because they live at the absolute extremities of the inhabited world, on the very shores of the Ocean. They are the most remote of peoples, situated right under the sun's melting orbit, which has scorched and blackened their skin."
Strabo further explains in Section 26 that while mathematically the global Earth is a sphere, the practical map of human habitation (the Oikoumene) behaves like a stretched out flat plane surrounded by a continuous sea. He states:"For those who live near the shores of Oceanus, the sun rises and sets directly at their horizon, and because there is no remaining distance or land barrier between them and the path of the sun, the solar heat meets them with immediate, unmediated fierceness."
This exact text confirms that ancient hybrid geography routinely blended a theoretical spherical Earth with a flat-plane map of human travel. In this dual model, the literal boundaries of the known world were believed to sit dangerously close to the low orbit where the sun physically rose and set.
The Direct Quranic Match: The Syriac Alexander Legend Claiming the Sun Close to the Eastern/Western Edges of the Earth
The closest historical parallel to the story of Dhulqarnain is found in a Christian text known as the Syriac Alexander Legend (or the Christian Legend Concerning Alexander). While this specific manuscript was composed in its final written form around 628 to 630 CE, which was exactly during the lifetime of Muhammad, the core narrative existed long before this date. The legend had been transmitted orally and compiled in earlier textual fragments throughout the preceding centuries. Much like the Quran and the Hadith collections existed as active oral traditions before being standardized into final written books, this Alexander romance was a widely circulating, ancient folk tale that had already populated the Near East for generations before it was officially penned down in Syriac. This text was famously translated by the prominent British academic Sir E.A. Wallis Budge in his 1889 volume, The History of Alexander the Great, Being the Syriac Version of the Pseudo-Callisthenes.
- The Western Journey: The Syriac text states that Alexander traveled to the western edge of the Earth until he reached a "foetid sea," which means a foul smelling, polluted ocean. The text explicitly notes that this is the place where the sun sets, describing the heavens opening so the sun could plunge down into this dark, murky water. You can review this full translated manuscript on the Syriac Alexander Legend Text on Archive.org.
- The Eastern Journey and the Scorched People: When Alexander reached the eastern edge where the sun rises, the Syriac legend describes the exact scene later recorded by the Islamic commentator Qatadah. Budge translates the passage from page 148 of the Syriac text as follows:
"When the sun rises, it is so close to the edge of the Earth that its rays melt iron and burn the vegetation. The people who live there have no houses or shelters; instead, as soon as the sun begins to rise, they flee and hide inside caves, underground tunnels, and deep waters to escape being burned to death by the sun’s direct proximity."
This passage can be read directly on the Syriac Alexander Legend Page on Answering Islam.
This historical context shows that the details found in Quran 18:86-90 and its early commentaries, such as people hiding in tunnels from the rising sun, an army dying from the heat, and the sun setting in a hot, murky spring, were not metaphorical descriptions or local weather observations. They were literal descriptions of flat earth physics copied directly from ancient mythologies and popular contemporary Syrian legends.
Hassan Radwan