In The Name Of Allah Most Gracious Most Merciful
Assalaamu alaykum wa rahmatuallahi wa barakatuhu

The Qahtaani

O you who believe! If any of you renounce your religion, Allah will bring forward a people whom He loves and who love Him, humble to the believers, fierce to the disbelievers, who strive in the Way of Allah and do not fear the blame of any censurer. That is the grace of Allah which He gives to whoever He wills. And Allah is Boundless, All-Knowing. (Qur’an 5:54)

The Prophet said, “The Hour will not come until a man from Qahtaan appears and rules the people.” (Muslim.)

Narrated Abu Hurayrah: Allah's Apostle said, "The Hour will not be established till a man from Qahtaan appears, driving the people with his stick." (Bukhari)

Reported by Mamar in the reference of Nuaym son of Hammad: "The Qahtaani is not lesser than the Mahdi."

Reported by Jabir, son of Majid As Sadafi: The Prophet, upon whom be blessings and peace, said: "After me there will be caliphs, and after the caliphs, princes and after princes, kings, and after kings, tyrants. Then, a man from the Family of my House will come and fill the earth with justice just as it had been filled with transgression. Then, the Prince after him is the Qahtaani and by He who sent me with the Truth he is not lesser than him." (At-Tabarani (in his large dictionary), Ibn Mandah, Abu Nuaym and Ibn Asakir.)

Note: The above narration clearly establishes that the Qahtaani appears and rules after the Mahdi, and thus, after the son of Maryam. This should remove any doubts about when the Qahtaani would appear and rule in relation to the other events.

Imam Ahmad reports from the hadeeth of Dhi Mikhbar, the son of the brother of an-Najaashi, from the Prophet (SAW) that he said, "This matter used to be amongst the red-skinned people but Allah removed it from them and placed it amongst the Quraysh but it shall return to them."

Abu Hurayrah said, “The Prophet said, ‘Day and night will not come to an end until a freedman called Jahjah holds sway.’” (Ahmad.)

Al-Bukhari narrated from Abu Hurayrah [radhiyallahu 'anhu], from the Prophet [sallallahu 'alayhi wa-sallam], that he said:

"The Hour will not come until a man comes from Qahtaan, driving the people with his staff."(Nu'aym ibn Hammad, Kitab al-Fitan, No. 124]

[125] And Nu'aym ibn Hammad narrated from 'Abd ar-Rahman ibn Qays as-Sadafi, from his father, from his grandfather, from the Prophet [sallallahu 'alayhi wa-sallam] that he said:

"The Qahtaani is after the Mahdi. By He Who sent me with the Truth, he is not lesser than him."(Nu'aym ibn Hammad, Kitab al-Fitan, No. 125]

 And he also narrated from Artah that he said:
"It has reached me that the Mahdi will live for forty years, then he will die on his bed. Then a man from Qahtan will come, with pierced ears, who will live according to the example of the Mahdi. He will remain for twenty years and then he will die, killed by the sword. Then a man will come from the household of the Prophet [sallallahu 'alayhi wa-sallam], rightly guided and of good example, who will conquer the city of Caesar. He will be the last leader from the Ummah of Muhammad [sallallahu 'alayhi wa-sallam]. During his time, the Dajjal will come out, and during his time, 'Isa ibn Maryam ['alayhis-salam] will descend."(Nu'aym ibn Hammad, Kitab al-Fitan, No. 122)

Allah Knows Best