Historian Robin Lane Fox states in his book Search for Alexander that "Alexander and Islam went hand in hand". Alexander is referred to in the Koran as the "two-horned prophet".

Muslim scholars have endorsed the identification of the two horned prophet with  Alexander the Great.

The Qur'an was revealed by God to Muhammad. The two-headed prophet  appears in sixteen verses of the Qur'an, specifically verses 18:83-98.

The Koran states that several Rabbis wanted to test Mohammad and asked him three questions:

"They (the rabbis) said, `Ask him about three things which we will tell you to ask, and if he answers them then he is a Prophet who has been sent (by Allah); if he does not, then he is saying things that are not true, in which case how you will deal with him will be up to you. Ask him about some young men in ancient times, what was their story? For theirs is a strange and wondrous tale. Ask him about a man who travelled a great deal and reached the east and the west of the earth. What was his story? And ask him about the Ruh (soul or spirit) -- what is it? If he tells you about these things, then he is a Prophet, so follow him, but if he does not tell you, then he is a man who is making things up, so deal with him as you see fit.'"

The famous story, in the Sira, goes that when Muhammad was informed of the three questions from the Rabbis, he declared that he would have the answers in the morning. However, Muhammad did not give the answer in the morning. For fifteen days, Muhammad did not answer the question. Doubt in Muhammad began to grow amongst the people of Mecca. Then, after fifteen days, Muhammad received the revelation that is Surah Al-Kahf ("the Cave"), the eighteenth chapter of the Qur'an. Surah Al-Kahf mentions the "People of the Cave," a strange story about some young men in ancient times who slept in a cave for many years. Surah Al-Kahf also mentions the Ruh, or soul/spirit. Finally, the surah also mentions "a man who travelled a great deal and reached the east and the west of the earth" - namely, Alexander the Great:

"Dhu al-Qarnain is Alexander the Greek, the king of Persia and Greece, or the king of the east and the west, for because of this he was called  'the two-horned one.."

 Alexander the Great was often depicted as one possessing horns, in particular the horns of Amon. Ancient Greek coins minted in the name of Alexander the Great depict Alexander with the distinctive horns of Amon on his head.

The reason that Alexander the Great was depicted with the horns of Amon in ancient Greek coinage is that in ancient Egypt Alexander was received as the son of the ancient Egyptian god Amon, and the god Amon was depicted as ram-headed. Alexander then styled himself as the son of Amon; "He seems to have become convinced of the reality of his own divinity and to have required its acceptance by others ... The cities perforce complied, but often ironically: the Spartan decree read, 'Since Alexander wishes to be a god, let him be a god.'"

The Qur'an describes a story about Alexander building a great gate near the "rising place of the Sun," between two mountains, in order to enclose the nations of Gog and Magog who "do great mischief in the earth." The relevant passages from Qur'an state:

"Thus were they [Gog and Magog] were made powerless to scale it or to dig through it [the gate]. He said this is a mercy from my Lord. But when the promise of my Lord comes to pass He will make it into dust. And the promise of my Lord is true ..." (Qur'an 18:98) and "...Until the Gog and Magog (people) are let through (the gate), and they swiftly swarm from every height (or advantage). Then will the True Promise draw nigh (of fulfilment). Then behold! The eyes of the Unbelievers will fixedly Stare in horror ..." (Qur'an 21:96-97)

"The Lord spake by the hand of the angel, [saying] ...The gate of the north shall be opened on the day of the end of the world, and on that day shall evil go forth on the wicked ... The earth shall quake and this door [gate] which thou [Alexander] hast made be opened ... and anger with fierce wrath shall rise up on mankind and the earth ... shall be laid waste ... And the nations that is within this gate shall be roused up, and also the host of Agog and the peoples of Magog shall be gathered together. These peoples, the fiercest of all creatures.

"The old men say, "Look, my lord the king, and see a wonder, this mountain which God has set as a great boundary." King Alexander the son of Philip said, "How far is the extent of this mountain?" The old men say, "Beyond India it extends in its appearance." The king said, "How far does this side come?" The old men say, "Unto all the end of the earth." And wonder seized the great king at the council of the old men ... And he had it in his mind to make there a great gate. His mind was full of spiritual thoughts, while taking advice from the old men, the dwellers in the land. He looked at the mountain which encircled the whole world ... The king said, "Where have the hosts [of Gog and Magog] come forth to plunder the land and all the world from of old?" They show him a place in the middle of the mountains, a narrow pass which had been constructed by God ..."

The rising of the Sun from the fetid sea

Rendition of Homer's view of the world (prior to 900 BC). The Homeric conception of the world involved a flat, circular Earth, surrounded by mountains. The mountains are, in turn, surrounded by Oceanus. The Sun emerges from underneath the Earth, traveling along the fixed dome of the sky, and is shown rising from Oceanus.

"Then he [Dhul-Qarnayn] followed a way until, when he reached the rising of the Sun, he found it rising upon a people for whom We had not appointed any veil to shade them from it ... " (Qur'an 18:89-90).

"... Until when the two-headed prophet reached the setting of the Sun, he found it set in a spring of murky water. Near it he found a People ..." (Qur'an 18:86)

Alexander's travels

Map of Alexander's empire. Alexander never marched far west of his native Greece, and his advances eastward ended at the fringes of India.

The Qur'anic and Christian legendary accounts both have it that Alexander the Great travelled to the ends of the Earth, in particular to the place on the Earth where the Sun sets (the west) and the place on the Earth where the Sun rises (the east). This allegory served the legendary accounts to convey the theme of Alexander's great exploits as a conqueror. In the context of the flat Earth, travelling to the places of the setting and rising of the Sun would imply having travelled across the entire world. However, many modern Muslims insist that the Qur'an's descriptions of the two-headed prohpet's  travels are just allegorical references to Alexander's travels towards the east and the west, and do not imply Dhul-Qarnayn travelled to the ends of the flat Earth. Naturally, the stories about Alexander's travels to the eastern and western extents of the world are a legendary tradition, which built up over centuries throughout the lands conquered by Alexander and beyond, after his death.

Muslim veneration of Alexander the Great

15th century Persian miniature painting from Herat depicting Iskander, the Persian name for Alexander the Great

As it has been noted, the early Muslim scholars generally identified the Dhul-Qarnayn of the Qur'an with Alexander the Great. In the centuries that followed, Dhul-Qarnayn was often thought of by Muslims as a Prophet of Islam. Early Islamic civilization would produce its own legendary traditions about Alexander the Great, particularly in Persia.