In the name of Allah, the Most Beneficent, Most Merciful.
The advent of Imam Mahdi is a universally accepted concept in Islam. There are numerous ahadees regarding the advent of Imam Mahdi. Every sect of Islam believes in the Advent of Imam Mahdi AHS. The Sunnis in general believe that Imam Mahdi has not appeared yet, and the Shias believe that Imam Mahdi has actually appeared but then went into hiding, and would reappear later on, and nobody knows when that would occur. Among the Sunni Muslims, there are different theories about the advent of Imam Mahdi, as to when he would appear and where he would appear and what he would accomplish. All those theories are based on various ahadees, and every one of them conveniently select the ahadees that fit their description. All of them agree on some basic facts, those are also based on ahadees, viz, Imam Mehdi would be in the progeny of Bibi Fatima, i.e., from the Ahl e Bait (from the house of the ProphetPBUH), HIS NAME WOULD BE THE SAME AS THAT OF THE PROPHET HIS FATHER'S NAME WILL BE THE SAME AS THE NAME OF THE FATHER OF THE PROPHETPBUH. Among several ahadees, this hadees also points out to the same fact. It is narrated by Abu Dawud that Razeen Abdullah had reported that the ProphetPBUH said that even if one day is left for the end of this world, Allah would prolong that day, so that a person from my family (Ahl-e-Bait) would be deputed, whose name would be my name and whose father's name would be my father's name.
The lineage of Imam Mahdi AHS goes straight to Hazrath Ali ibn-e-Abu Talib RZ through Imam Hussain RZ, Imam Zainul-Abideen RA, Imam Jaffer Sadiq RA, and Imam Musa Kazim RA, to name a few. Therefore, Hazrath Syed Muhammed Jaunpuri Mahdi AHS is a Hussaini Syed.
As we know, the name of our beloved ProphetPBUH is MUHAMMAD, and his father's name is ABDULLAH. So, whoever claims to be the PROMISED MAHDI, must fit this description. The name of our Imam Mahdi al Mawood is Syed Muhammad and his father's name is Syed Abdullah, and he is the direct descendant of Hazrath Imam HussainRZ. Thus, he exactly fits the criteria defined by our beloved ProphetPBUH. Now there is a little twist. The title of Hazrath Syed Abdullah was SYED KHAN. This gave a lot of opponents and objectors an opening to dispute the claim of ImamunaAHS as being the true Mahdi, claiming that he does not fit the basic criteria of being the son of Abdullah. This objection is just for the sake of an objection (aiteraaz baraai aitiraaz) because the objectors are not ignorant, they needed an excuse to discredit him and his claim of being the PROMISED MAHDI. Starting with Sirajul Absaar by Hazrath Abdul Malik SujawandiRZ, a lot has been written by our Mahdavia scholars in the past to rebut all the baseless arguments of the opposing scholars. Writing one more article would be superfluous. But there are a couple of points that could be discussed here. One is that SYED KHAN per se could not be a given name, and the second one is that the title of SYED KHAN is proved with historical evidence.
Khan is usually a title and an honorific bestowed by kings and emperors on a person who distinguishes himself in the service of the state. Khan is also the last name of the whole community of people who are known as pathans or Pashtun, belonging to the area of Pakhtunistan and its environs in Afghanistan. There are numerous tribes among them, and each tribe or clan is identified by the ZAI suffix and are Khan by ancestry. When Timuchin became the overlord of all the Mongol people, he assumed the title of Khan, with the name of Chengis Khan. Here the word KHAN denotes a leader or a chieftain or an overlord. Then his descendants had the same title for several generations, heading their own Khanates. A khanate was a political entity ruled by a Khan.
In our own Mahdavia community we have pathans of various tribes or clans, like Yahyazai, Alizai, Mahmandzai, Sandozai etc. They are the descendants of the Pathan tribes who migrated from Afghanistan, and have overwhelmingly retained their identity as a very distinct class of people, and in the past distinguished themselves in the service of the state they served, and were rewarded with estates (Jagir) and titles. More recently, most notable of them was Nawab Bahadur Khan, who was endowed with the honorific title of Nawab Bahadur Yar Jung. The Nawabs of Palanpur were the rulers of Palanpur princely state of Palanpur in Gujarat, India. They belonged to the Lohani Pashtun tribe. The last ruling Nawab was Nawab Taley Muhammed Khan Bahadur, who ruled until the independence of India in 1947. These are the original Pathans by ancestry, their last name is Khan, descendants of the tribes who migrated to India.
The tradition of bestowing the title of the Khan goes a long way back, maybe more than a millennium. These are the titular Khans because Khan is an honorific. Because the pathans or the Khans distinguished themselves in the service of the kings they served, the very name or title Khan became an honorific and a title of dignity and status. In recent past during the Asaf Jahi period in Hyderabad, Syed Esa served in the army of the Nizam of Hyderabad and distinguished himself and was awarded the title of Meeran Yar Jung. Esa Miyan Bazar in Hyderabad was established by him and is named after him. His son Syed Abul Fatah also served in the army of the Nizam of Hyderabad, distinguished himself by his service to the state and was awarded the title of Fatah Yab Khan. He thus became a titular Khan, not by ancestry. Fatah Yab Khan Bazar in Hyderabad India is named after him. So, the people who are Pathan are Khan by ancestry, and then there are people who are TITULAR KHAN.
The whole purpose of this article is to provide historic evidence that SYED KHAN is a title, not a given name. In the Maasir e Alamgiri (A History of Emperor Aurangzeb Alamgir, the sixth Mughal Emperor) (https://archive.org/details/in.ernet.dli.2015.62691/page/n145/mode/2up) it is mentioned on page 140 that Syed Nur Muhammad of Bariha got the title of SAYYID KHAN. It also mentions on the same page the two sons of a Haiderabad grandee, Sayyid Muzaffar got high Mansabs and title of ASALAT KHAN and NAJABAT KHAN. These two persons were Syed by ancestry but were made titular KHANS. It becomes clear that Khan in fact becomes part of the title. It deserves to be noted that SYED KHAN per se could not be a given name, never has been a given name in the whole history. It is a well-known fact that, when a person is awarded a title, that person generally comes to be known by the titular name. One instance here would be of our own Nawab Bahadur Khan. He was a Panni Pathan by ancestry and came from the noble family of Hyderabad Nawabs. But after he was endowed with the title of Nawab Bahadur Yar Jung, he generally became known by his titular name.
If somebody makes an objection just for the sake of an objection, that person is apparently not prepared to listen to any reasoning. When Imamuna Alaihis Salam was asked the same question by the opposing scholars (Ulema), he did not reason with them. Instead, he made a counter argument, and told them to ask Allah, why HE made the son of Syed Khan, the Mehdi. Hence, it becomes clear that there is no use trying to reason with a person posing such a ridiculous question. In the end it would be advisable to go with the counter argument put forward by Imamuna AHS.