Salam alaikum,
Someone questioned me that, how was ibn Taymiyyah able to prophesize about the Tatars? Did he possess knowledge of Unseen? Or received revelation?
The answer to this doubt is that, It wasn't Ibn Taymiyyah who prophesized about Tatars, but it was Prophet Muhammad(saw), and it was one of his prophesy which came true in the time of Ibn Taymiyyah, due to which Ibn Taymiyyah was certain about them.
Ibn Taymiyyah understood about the hadeeth regarding, the war between the Muslims and a reddish people with small eyes, wearing sandals made of hair, as a reference to the Mongol Tatar invasion of the Islamic lands.)
Allah's Messenger (ﷺ) said, "The Hour will not be established until you fight with the Turks; people with small eyes, red faces, and flat noses. Their faces will look like shields coated with leather. The Hour will not be established till you fight with people whose shoes are made of hair."[Sahih al-Bukhari 2928]
Buraidah said: In the tradition telling that people with small eyes, i.e. the Turks, will fight against you, the prophet (ﷺ) said: You will drive them off three times till you catch up with them in Arabia. On the first occasion when you drive them off those who fly will be safe, on the second occasion some will be safe and some will perish, but on the third occasion they will be extirpated, or he said words to that effect.[Sunan Abi Dawud 4305]