Who was zhul qarnayn as mentioned in the quran, according to history?

And why is it not Alexander the great?

he was not Alexander. they had a different belief. Alexander was a pagan, while Zulkarnaen was a prophet of Allah

cause Alexander the great believed himself to be the son of ares the god of war

Alexander and Bulganin are two diff rent people.
one foll wed Islam and the other Christianity

Zul Qarnayn was actually Cyrus the great...
I have to go dig between my old answers... BC I've answered this exact question way back in 2007-2008... so I'll be back with the whole thing... CZ am not in the mood to open books and write down sources for u... it's easier to copy paste..




EDIT:
I couldn't find my answer to copy it for u... so I came back here... and saw that dear Dr Doctor has already answered you... so there you go...

Cyrus the great

Cyrus was able to combine the territories of Persia and Media for the first time and as a symbol of that unification of states, he wore that crown of two horns, and as such was known as Dhul Qarnain by the Semitic people of his time.

One of the great scholars of Islam, the late Mowlana Abul Kalam Azad, the president of Indian National Congress during the British rule, in his taffies (explanation of the verses of the Qur'an) provide enough conclusive evidences to suggest that Dhul Qarnain was none other than Emperor Cyrus of Persia. He built a wall in the Caucasus, which today probably goes more by the name of Dariel Pass, to stop the marauding activities of Gog and Magog (a Mongoloid race).

No one knows for sure who was Zhul Qarnayn. He was a believer in Allah and a good natured general of some country's army.

http://www.youtube.com/watch?v=szuGxSBowI8