O Aḥnaf! It is as though I see him advancing with an army which has neither dust nor noise, nor rustling of reins, nor neighing of horses. They are trampling the ground with their feet as if they are the feet of ostriches.
قال الشريف : يومئ بذلك (عليه السلام) إلى صاحب الزّنْج.
as-Sayyid ar-Raḍī says : Amīr al-mu’minīn pointed to the Chief of the Negroes, (Ṣāḥibu’z-Zanj). 
Then Amīr al-mu’minīn said : Woe to you (the people of Baṣrah’s) inhabited streets and decorated houses which possess wings like the wings of vultures and trunks like the trunks of elephants; they are the people from among whom if one is killed he is not mourned and if one is lost he is not searched for. I turn this world over on its face, value it only according to its (low) value, and look at it with an eye suitable to it.
منه ويومئ به إلى وصف الاتراك : كَأَنِّي أَرَاهُمْ قَوْماً كَأَنَّ وَجُوهَهُمُ الْـمَجَانُّ الْمُطَرَّقَةُ، يَلْبَسُونَ السَّرَقَ وَالدِّيبَاجَ، وَيَعْتَقِبُونَ الْخَيْلَ الْعِتَاقَ، وَيَكُونُ هُنَاكَ اسْتِحْرَارُ قَتْل،حَتَّى يَمْشِيَ الْـمَجْرُوحُ عَلَى الْمَقْتُولِ، وَيَكُونَ الْمُفْلِتُ أَقَلَّ مِنَ المَأْسُورِ!
[A part of the same sermon referring to the Turks (Mongols) :] I  can see a people whose faces are like shields covered with rough-scraped skins. They dress themselves in silken and woollen clothes and hold dear excellent horses. Their killing and bloodshed shall take place freely till the wounded shall walk over the dead and the number of runners-away shall be less than those taken prisoner:
فقال له بعض أصحابه: لقد أَعطيت يا أميرالمؤمنين علم الغيب! فضحك (عليه السلام)، وقال للرجل ـ وكان كلبياً :
One of his companions said to him: O Amīr al-mu’minīn, you have been given knowledge of hidden things. hereupon Amīr al-mu’minīn laughed and said to the man who belonged to the tribe of Banū Kalb :
O brother of Kalb! This is not knowledge of hidden things (‘ilmu’l-ghayb ),  these matters have been acquired from him (namely in Prophet) who knew them. As regard knowledge of hidden things, that means knowledge of the Day of Judgement, and the things covered by Allāh in the verse : Verily, Allāh is He with Whom is the knowledge of the Hour . . . (Qur’ān, 31:34)
Therefore, Allāh alone knows what is there in the wombs, whether male or female, ugly or handsome, generous or miserly, mischievous or pious, and who will be the fuel for Hell and who will be in the company of the Prophets in Paradise. This is the knowledge of the hidden things which is not known to anyone save Allāh. All else is that whose knowledge Allāh passed on to His Prophet and he passed it on to me, and prayed for me that my bosom may retain it and my ribs may hold it.
 ‘Alī ibn Muḥammad was born in the village of Warzanīn in the suburbs of Ray, and belonged to the Azāriqah sect of the Khārijites. He claimed to be a sayyid (descendant of the Holy Prophet) by showing himself the son of Muḥammad ibn Aḥmad al-Mukhtafī ibn ‘Īsā ibn Zayd ibn ‘Alī ibn al-Ḥusayn ibn ‘Alī ibn Abī Ṭālib, but the experts on lineality and biographers have not accepted his claim to being a sayyid and have given his father’s name as Muḥammad ibn ‘Abd ar-Raḥīm instead of Muḥammad ibn Aḥmad. The former was from the tribe of ‘Abd al-Qays and had been born of a Sindī maidslave.
‘Alī ibn Muḥammad rose as an insurgent in 255 A.H. in the reign of al-Muhtadī Billāh and associated with him the people from the suburbs of Basrah on promise of money, wealth and freedom. He entered Baṣrah on the 17th Shuwwāl, 255 A.H. killing and looting, and in only two days he put to death thirty thousand individuals, men, women and children, and displayed extreme oppression, bloodshed, savageness and ferocity. He dismantled houses, burnt mosques, and after continuous killing and devastation for fourteen years, was killed in the month of Safar, 270 A.H. in the reign of Muwaffaq Billāh. Then people got rid of his devastating deeds.
Amīr al-mu’minīn’s prophecy is one of those prophecies which throw light on his knowledge of the unknown. The details of his army given by Amīr al-mu’minīn namely that there would be neither neighing of horses nor rustling of weapons therein is a historical fact. The historian aṭ-Ṭabarī has written that when this man reached near al-Karkh (a sector of Baghdād) with the intention of insurrection, the people of that place welcomed him, and a man presented him a horse for which no rein could be found despite a search. At last he rode it using a rope for the rein. Similarly there were at that time only three swords in his force —one with himself, one with ‘Alī ibn Abān al-Muhallabī, and one with Muḥammad ibn Salm, but later they collected some more weapons by marauding.
 This prophecy of Amīr al-mu’minīn is about the attack of the Tartars (Mongols) who were inhabitants of the Mongolian. desert in the north west of Turkistan. These semi-savage tribes lived by marauding, killing and devastating. They used to fight among themselves and attack neighbouring areas. Each tribe had a separate chief who was deemed responsible for their protection. Chingiz Khān (Temujin) who was one of the ruling chiefs of these tribes and was very brave and courageous had risen to organize all their divided tribes into one, and, despite their opposition he succeeded in overpowering them through his might and sagacity. Collecting a large number under his banner he rose in 606 A.H. like a torrent and went on dominating cities and ruining populations till he conquered the area upto North China.
When his authority was established he offered his terms of settlement to ‘Alāu’d-Dīn Khwārazm Shāh, ruler of the neighbouring country of Turkistan, and through a deputation concluded an agreement with him that Tartar traders would be allowed to visit his country for trade and their life and property would not be subject to any harm. For some time they traded freely without fear but on one occasion ‘Alāu’d-Dīn accused them of spying, seized their goods and had them killed by the Chief of Atrār. When Chingiz Khān learnt of the breach of the agreement and the killing of Tartar merchants his eyes cast forth flames and he began trembling with rage. He sent word to ‘Alāu’d-Dīn to return the goods of the Tartar merchants and to hand over to him the ruler of Atrār. ‘Alāu’d-Dīn, who was mad with power and authority, did not pay any heed, and acting short-sightedly killed even the plenipotentiary of Chingiz Khān. Now Chingiz Khān lost all patience and his eyes filled with blood. IIe rose with his sword in hand, and the Tartar warriors leapt towards Bukhārā on their speedy stallions. ‘Alāu’d-Dīn came out with four hundred thousand combatants to face him but could not resist the incessant assaults of the Tartars, and having been vanquished only after a few attacks ran away to Nīshābūr across the river Jaxartes (Sīḥūn). The Tartars smashed Bukhārā and razed it to the ground. They pulled down schools and mosques, burning to ashes the houses and killing men and women without distinction. Next year they assaulted Samarqand and devastated it completely. After the flight of ‘Alāu’d-Dīn, his son Jalālu’d-Dīn Khwārazm Shāh had assumed the reins of government. The Tartars chased him also, and for ten years he fled from one place to the other but did not fall in their hands. At last he crossed over the river out of the boundaries of his realm. During this time the Tartars did their utmost to ruin populated lands and to annihilate humanity. No city escaped their ruining and no populace could avoid their trampling. Wherever they went they upset the kingdom, overthrown governments, and in a short time established their authority over the northern portion of Asia.
When Chingiz Khān died in 622 A.H. his own son Ogedei Khān succeeded him. He searched out Jalālu’d-Dīn in 628 A.H. and killed him. After him Mongka Khān, the son of the other son of Chingiz Khān, occupied the throne. After Mongka Khān, Quhilai Khān succeeded to a part of the country and the control of Asia fell to the share of his brother Hūlāgū Khān. On the division of the whole realm among the grandsons of Chingiz Khān, Hūlāgū Khān was thinking of conquering Muslim areas when the Ḥanafite of Khurāsān in enmity with the Shāfi‘ite invited him to attack Khurāsān. He therefore led an assault on Khurāsān, and the Ḥanafite, thinking themselves to be safe from the Tartars, opened the city gates for them. But the Tartars did not make any distinction between Ḥanafite and Shāfi‘ite and killed whoever fell to their hands. After killing most of its population they took it in occupation. These very differences between the Ḥanafite and the Shāfi‘ite opened for him the door of conquest upto Iraq. Consequently, after conquering Khurāsān his courage increased and in 656 A.H. he marched on Baghdād with two hundred thousand Tartars. al-Musta‘ṣim Billāh’s army and the people of Baghdād jointly faced them, but it was not in their power to stop this torrent of calamity. The result was that the Tartars entered Baghdād on the day of ‘Āshūrā’ carrying with them bloodshed and ruin. They remained busy in killing for forty days. Rivers of blood flowed in the streets and all the alleys were filled with dead bodies. Hundred of thousands of people were put to the sword while al-Musta‘ṣim Billāh was trampled to death under foot. Only those people who hid themselves in wells or underground places and hid from their sight could survive. This was the devastation of Baghdād which shook the ‘Abbāsid Kingdom to its foundation, so that its flag could never fly thereafter.
Some historians have laid the blame of this ruin on Ibn al-‘Alqamī (Abū Ṭālib, Muḥammad ibn Aḥmad al-Baghdādī), the minister of al-Musta‘ṣim Billāh, by holding that, moved by the genral masses of the Shī‘ahs and the ruin of al-Karkh sector (of Baghdād), he invited Hūlāgū Khān through the latter’s minister, the great scholar Nasīru’d-Dīn Muḥammad ibn Muḥammad aṭ-Ṭūsī, to march on Baghdād. Even if it be so, it is not possible to ignore the historical fact that before this the ‘Abbāsid Caliph an-Nāsir Lidīni’llāh had initiated the move for the attack on the Muslim areas. When the Khwārazm Shāhs declined to acknowledge the authority of the Caliphate he had sent word to Chingiz Khān to march on Khwārazm, from which the Tartars had understood that there was no unity and cooperation among the Muslims. Thereafter the Ḥanafite had sent for Hūlāgū Khān to crush the Shāfi‘ite as a consequence of which the Tartars secured control over Khurāsān,and prepared the way to march towards Baghdād. In these circumstances to hol only Ibn al-‘Alqamī responsible for the ruination of Baghdād and to ignore the move of an-Nāsir Lidīni’llāh and the dispute between the Ḥanafite and the Shāfi‘ite would be covering up the facts, when in fact the cause for the ruin of Baghdād was this very conquest of Khurāsān, whose real movers were the Ḥanafite inhabitants of the place. It was by this conquest that Hūlāgū Khān had the courage to march on the centre of Islam; otherwise it cannot have been the result of a single individual’s message that he assaulted an old capital like Baghdād, the awe of whose power and grandeur was seated in the hearts of a large part of the world.
 To know hidden things on a personal level is one thing, while to be gifted by Allāh with knowlege of any matter and to convey it to others is different. The knowledge of the future which the prophets and vicegerents possess is gained by them through Allāh’s teaching and informing. Allāh alone has knowledge of events which are to happen in the future. Of course, He passes this knowledge on to whoever He wills. Thus He says :
(He alone is) the “Knower of the unseen, neither doth He reveal His secrets unto any (one else) save unto that one of the Messengers whom He chooseth . . .” (Qur’ān, 72:26—27)
In this way Amīr al-mu’minīn also received knowledge of the future through the instructions of the Prophet or inspiration from Allāh, for which these words of Amīr al-mu’minīn stand evidence. Of course, sometimes it is not proper or expedient to disclose certain matters and they are allowed to remain under a veil. Then no one can be acquainted with them as Allāh says:
Verily, Allāh is He with Whom is the knowledge of the Hour and He sendeth down the rain, and knoweth He what is in the wombs; and knoweth not any soul what he shall earn the morrow, and knoweth not any soul in what lands he shall die: Verily Allāh is All-knowing, All-aware. (Qur’ān, 31:34)