"An army carrying black flags will come from Khurasan, no power will be able to stop them and they will finally reach Jerusalem where they will erect their flags"  

 [Tirmizi Shareef vol 2 hadeeth 152]

"If you see the Black Banners coming from Khurasan go to them immediately, even if you must crawl over ice, because indeed amongst them is the Caliph, Al Mahdi."

[Narrated on authority of Ibn Majah, Al-Hakim, Ahmad]

"The black flags will come from the East, led by mighty men, with long hair and beards, their surnames are taken from the names of their home towns and their first names are from Kunya"

[Asmal Masalik Lieyyam Mahdiyy Maliki Li Kull-id Dunya Biemrillah-il Malik, Qalda bin Zayd]

"An army carrying black flags will come from Khurasan, no power will be able to stop them…"

[Tirmizi Shareef vol 2 Hadeeth 152]