亚历山大现在已经下定决心，要把他的军队直接带到波斯帝国的中心城市波斯波利斯。亚历山大的一位将军带领他的军队向南绕行设拉子，亚历山大和2万名精锐士兵抄近路穿过扎格罗斯山脉的一条狭窄小道，这条小道被称为波斯之门。

亚历山大深陷山口，才意识到自己掉进了陷阱。波斯人在缺口最窄的地方筑起了一堵墙，正等着他。石块、标枪和大炮像雨点般落在毫无戒备的部队身上。亚历山大的手下丢下死者，撤退了。

必须有另一种方法，但亚历山大审问囚犯却无济于事。最后，一位当地牧羊人走了出来。他提出，也许有办法；山口后面的一条狭窄而艰难的小路。亚历山大问道，有一支军队能通过那里吗。绝对不是，牧羊人回答。亚历山大命令他的士兵沿着这条路线前进。

亚历山大的军队不顾一切困难，在夜间穿越了这条秘密而危险的小径，并在波斯人身上关闭了自己的陷阱。这条路到底在哪里？我们当地的导游一直争论到深夜。但是，早晨发现我们在路上，他们中的一个起初认为不可能。他说，亚历山大是一月份来到这里的。雪太深了。然而，这必须是唯一的办法。

Alexander had now set a determined pace that would bring his army straight into heart of the Persian empire, the city of Persepolis. While one of Alexander's generals lead his troops on a southerly loop through Shirazz, Alexander and 20,000 elite soldiers took a short cut through a narrow path in the Zagros Mountains known as the Persian Gates.

Alexander was deep into the pass before he realized he had fallen into a trap. The Persians had built a wall at the narrowest part of the gap and were waiting for him. Stones, javelins, and artillery rained down on the unsuspecting troops. Leaving their dead behind, Alexander's men withdrew.

There had to be another way, but Alexander interrogated prisoners to no avail. Finally, a local shepherd came forward. There might be a way, he offered; a narrow and difficult path around the back of the pass. Could an army pass through there, Alexander asked. Absolutely not, the shepherd replied. Alexander ordered his men forward on that very route.

Against all odds, Alexander's army crossed the secret and treacherous trail at night and closed his own trap on the Persians. Exactly where was this path? Our local guides debated this well into the night. But, morning found us on the path one of them first thought impossible. Alexander came here in January, he said. The snows would be too deep. Yet this had to be the only way.