The large army of the Tatars started to move from its main bastions in Hamadan westward where it crossed the mountains West of Iran, then entered the borders of Iraq from North-East, crossed Irbil, and reached Mawsil, which was loyal to Hulagu, and crossed the Tigris, the first natural obstacle in this region. It was actually dangerous, and the army had to cross it in a very secure area, because there was a great risk in having a large army cross it; and no area was better than this, which was perfectly loyal to Hulagu!

Then, the army of the Tatars marched alongside the West bank of the Tigris in the territory of Al-Jazeerah till it reached Nisibis (currently South of Turkey), about 170 kilometers South of Mayyafariqin. Thus, Hulagu came close to the army of his son, but surpassed it for he was assured about its power.
Hulagu occupied Nisibis almost with no resistance. Then he moved westward to occupy Haran, then Edessa, and then Al-Bireh, all of which lie South of Turkey. Hulagu then had to pass through all those Turkish cities in order to reach Aleppo from North, and be assured that there would be no Islamic forces at his back.
At Al-Bireh, Hulagu crossed the wide Euphrates from the East to the West, the second natural obstacle in the region. Then he moved Southward, West of Euphrates, breaking through the Syrian-Turkish borders, towards the impregnable city of Aleppo, as close to the Turkish borders (as about only 50 kilometers).

It took the Tatars one year, i.e. 657 A.H., to pass through the Persian, then the Iraqi, then the Turkish and then the Syrian territories. In Muharram 658 A.H., Hulagu arrived in Aleppo, and besieged the Muslim city from all sides. But Aleppo refused to surrender to Hulagu. Resistance was led by Toran Shah, who, though the paternal uncle of An-Naasir Yoosuf, was a real Mujaahid, unlike his nephew. The Tatars set up their catapults around Aleppo, and started shelling it relentlessly. An-Naasir Yoosuf was camping with his army as far as 300 kilometers to the South, near Damascus!

http://300035.dotdothktrade.tech/en/artical/20815/way-aleppo