It could also mean the possessor of two nations so that’s why many people believed he was Cyrus or Darius they were also monotheist and Josephus and the Bible talks about dhulqarnain see Daniel 8 and Josephus was known to hellenise Jewish history and the Greeks and romans hated the Persians.I’ll watch it soon, thank you.
But even if the Syriac story came after this Surah was revealed, there were still other versions that date centuries prior. I remember reading about Josephus’ version in the first century containing the story of Alexander, Yajuj and Majuj and the wall between a valley. All within the story of Dhul Qarnayn.
Dhul Qarnayn also means “Two Horned one”
And coins of Alexander have been found depicting him with horns like these:
View attachment 261569
Not to mention tafsirs like al-Jalalayn also believed it was Alexander