我只能说,建议楼主再多看点。
历史出处,普鲁塔克的记载:Alexander continued seven moneths travelling upon the rivers , to go see the great sea Oceanus . (亚历山大继续在河流上航行了七个月,打算去看伟大之海俄刻阿诺斯。)
奥罗修斯的记载:Post haec Indiam petit, ut Oceano ultimoque Oriente finiret imperium。(粗略地说:“此后,他前往印度,以将俄刻阿诺斯和东方的尽头作为他帝国的边界。”)
最终收束到部分历史学家(如Green, Peter的《Alexander of Macedon 》, 1991)的结论,即为:“Alexander’s original vision of empire had been to the east, though, to the ends of the world and the Great Outer Sea, as described by his boyhood tutor Aristotle. ”(然而,正如他童年时期的导师亚里士多德所描述的那样,亚历山大最终的帝国愿景是一直向东,直到抵达世界尽头的伟大外海。)
2000 年 BBC的纪录片In the Footsteps of ATG也引用了这个说法。

话说wiki都有的玩意,怎么那么多人还拿来说事的。
然后衍生出的神话传说记载。随便举个例,基督背景的亚历山大罗曼史。
He [Alexander] said to them [the nobles]: "This thought has arisen in my mind, and I am wondering what is the extent of the earth, and how high the heavens are ... and upon what the heavens are fixed ... Now this I desire to go and see, upon what the heavens rest, and what surrounds all creation." The nobles answered and said to the king, ... "As to the thing, my lord, which thy majesty desires to go and see, namely, upon what the heaveans rest, and what surrounds the earth, the terrible seas which surround the world will not give thee a passage; because there are eleven bright seas, on which the ships of men sail, and beyond these there is about ten miles of dry land, and beyond these ten miles there is the foetid sea, Okeyanos (the Ocean), which surrounds all creation. Men are not able to come near to this foetid sea ... Its waters are like poison and if men swim therein, they die at once."
大意:亚历山大想看遍世间,贵族们回答,世界尽头为环绕万物的俄刻阿诺斯,人类不可抵达。