NOTE: For a synopsis of this document and more information about the history of Alamut please refer to my Index to the History of Alamut.
[Reader warning: subcontinent English below]
SAYYIDNA HASAN BIN SABBAH
In his words Mowlana Abdur Razak Kanpuri on behalf of Sayyidna Hasan bin Sabbah says: "Khawaja Nizamul Mulk and Hakim Umar Khayyam are those sky shining stars who came to be known as radiants of an empire. In comparison to them, after some frustrations, Hasan bin Sabbah achieved, that success which was only the result of his virtues and skill, extraordinary wisdom and God given intelligence."
There is a difference of opinion with the historian about the correct date of birth of Sayyidna Hasan bin Sabbah. Some historians presume that he was born in 432 A.H., while others surmise that it was 445 A.H. Dr. W. Ivanow says that Sayyidna Hasan bin Sabbah was born after 440 A.H.  On the other hand, Dr. Bernard Lewis says that Sayyidna Hasan was born approximately by in the middle of 1100 C.E. i.e. 442 or 443 A.H.  But if we take into consideration the date of death of Hasan bin Sabbah namely 517 A.H. - 1124 C.E. for which all historians are unanimous , when he was 90 years of age, then his year of birth could be ascertained to be in 428 A.H. - 1034 C.E. 
We are unable to find any information regarding his childhood or ancestry, but some history books describing his ancestry say that Hasan bin Aly bin Mohammed bin Ja'far bin Husayn bin Sabbah al-Hamari was connected with the dynasty of the king of Yaman. However, when people began to mix up Hasan bin Sabbah's ancestry with that of the lmam, he himself is reported to have said: "Instead of becoming an unlawful descendant of the Imam I would prefer to be his devoted servant." 
Sayyidna Hasan was born in an lthna 'Ashari family' of Ray. His father was a learned leading personality of lthna 'Ashari faith. His father took keen interest in the education of Sayyidna Hasan and from the age of 7 to 17 he prosecuted his study at home.  With vigorous effort and resistance he acquired perfect knowledge of the then prevailing sciences of mathematics, philosophy and languages. lbn Athir says Hasan was an intelligent man who had perfect command over palmistry and mathematics (in the wider sense). 
Enemies of Sayyidna Hasan bin Sabbah have concocted unbelievable stories and sayings which go to show that there was nothing else behind it, save the malign intention of defaming Hasan. One famous and popular story is that Hasan acquired knowledge from Imam Maufique Annishapuri and that Nizamul Mulk and Umar Khayyam were his colleagues. And it is also said that during their collegiate they arrived at a joint decision that after acquiring the knowledge if they took part in politics, they would cooperate with each other and if any of them attained a prosperous fortune, he would have to assist his companions. It is stated upon this unfounded basis that when Nizamul Mulk acquired the post of 'Wizarat' i.e., he became Minister in the Saljuq reign, Umar Khayyam approached him and became successful in getting sanctioned a good amount of finance toward his pension, which is wrong . Moreover that, Sayyidna Hasan also approached Nizamul Mulk and reminded him of the promise. It is said that Nizamul Mulk offered him the rule over an Islamic province but Sayyidna Hasan refused to accept it and desired a post in the king's court, for he was covetous for the position of 'Wizarat'. Nizamul Mulk tried for this also and got him fixed.
If we review it from the view of chronology we would find that Nizamul Mulk was born in 408 A.H. , while the date of birth of Sayyidna Hassan is arrived at being either 427 A.H. or thereafter. This shows that Nizamul Mulk was almost 20 or more years older than he was. It is impossible that with the difference of such a gap of years in age Sayyidna Hasan and Nizamul Mulk could have been colleagues at school. Over and above this, the prescribed period of education of Nizamul Mulk is 440 A.H. and the learning center of Imam Maufique had already ended in 440 A.H.  As mentioned heretofore that the date of birth of Sayyidna Hasan was 428 A.H. and that for 17 years, i.e., until 445 A.H., he was acquiring education at home, it makes it quite obvious that before Sayyidna Hasan reached Nishapur that lmam Maufique had expired and his learning center was closed and hence the question of collegiate of Nizamul Mulk and Sayyidna Hasan could not arise at all.
History has preserved the names of the teachers of Nizamul Mulk and also about his education, but the mention of lmam Maufique as his teacher is made nowhere.  Then how is it possible that Sayyidna Hasan bin Sabbah remained a colleague of Nizamul Mulk in the tuition of Imam Maufique. It is equally false that Nizamul Mulk tried for Sayyidna Hasan to secure the service in the Saljuq Court. The entering of Sayyidna Hasan in the Saljuqui Court was entirely due to his own efforts and qualification and not because of the help of Nizamul Mulk, as it is generally presumed. Sayyidna Hasan secured this position at the age of 30 years, and it goes to show how vast his knowledge and experience were.
All historians and biographers are unanimous that Sayyidna Hasan was an outstanding, highly qualified authority on sciences of politics and mathematics. He was expert also in administration. His way of organization was very precise and up to the mark. He would prefer nothing except carrying out his work up to the mark and to fulfil his duties. Due to his such qualities in the performance of his responsibilities, the ruler Malik Shah was highly impressed by him and used to take his counsel on the matters of administration, especially economic planning; while contrary to this Nizamul Mulk was breeding jealousy and enmity against Sayyidna Hasan and was considering him to be an obstacle in his way; therefore he was anxiously contemplating doing away with him. With this purport Nizamul Mulk used to find faults with him and reprimand him. In this behalf an example is quoted here below:
Once Sultan called Wazir-e-Azam and ordered him to reorganize various departments of his Government and enquired of him as to the time he would require to complete it. Wazir asked for two years time. Sultan considered it to be too long as he was anxious to get it done quickly. As he was aware of the capability of Sayyidna Hasan, he called him and enquired as to whether he would be able to do this job soon enough. Sayyidna Hasan was willing and was ready to complete it within 40 days.  Sultan was wonderstruck and said "it seems that you have not properly understood the nature of work: Wazir-e-Azam pleads for longer time than compared to yours." Sayyidna Hasan assured Sultan that it would not take more than a month to complete it. Sultan was highly pleased with him and ordered the staff of his administration to supply Sayyidna Hasan with what ever papers and documents he required. So Sayyidna Hasan started the work with great pleasure.
Plot of Nizamul Mulk
On the other hand, Nizamul Mulk got horrified with this incident and feared of losing his office of Wizarat, for he was well aware of the unique ability and intelligence of Sayyidna Hasan and was certain that he would succeed in his task. Therefore, he tried to remove Sayyidna Hasan from the services through a plot. He contemplated confusing the documents of the scheme worked upon by Sayyidna Hasan and he arranged this plot through his confidential person and asked him to be friendly with the slave of Sayyidna Hasan. When his confidential person secured the assurance of the slave of Sayyidna Hasan, one day he seized the opportunity of confusing the documents of Sayyidna Hasan.  However, Sayyidna Hasan was unaware of this and when he came to present the documents before Sultan, Sayyidna Hasan was taken aback to find that the papers were not in order as arranged by him. When Sultan demanded the documents Sayyidna Hasan could not present them instantaneously, by which Nizamul Mulk got the opportunity of prejudicing Sultan Malik Shah against Sayyidna Hasan and said that if Sultan were to trust such persons who do not know anything then surely he would fall prey to their intrigues and snares. In this way Nizamul Mulk began to poison the ears of Sultan with the result that Sultan ordered to arrest Sayyidna Hasan. He would have slain him if he had no love for Sayyidna Hasan and regard for his work. Ultimately Sayyidna Hasan slipped away and fled to Ray.
Religious arguments and discussions
Before the period of Sayyidna Hasan, Islamic ideas were tested through philosophy and split into many schools of thought, just as Mu'tazili, Ashari, etc., and in the period of Banu Abbas, due to the problems arising from different interpretations of the Holy Quran, wide fields of arguments and discussions were created. Sayyidna Hasan also being a scholar, took part in the discussions and was advocating lthna 'Ashari school of thought, but he could not remain firm on this belief, neither was he satisfied with the doctrines of Mu'tazila and 'Asha'ra. To him doctrines of these schools of thought were of no avail to him. Thus, he was deeply entangled in confusion.
Sayyidna Hasan embracing Ismaili Faith
Since from the period of Ummayyads Iran had become the centre of Shi'ism. Ismaili Da'is vigorously propagated Ismaili faith in Tabaristan, Delam, Ray, etc., and they were holding arguments with authorities of different schools of thought. Sayyidna Hasan was also prompted to hold discussions with the Da'is and he was all praise for the capabilities, learned qualities and the art of deliberations of the Da'is. After all this, he was so inclined that he came to be magnetised towards Ismaili faith, in as much as he commenced grasping tenets of Ismaili concepts through Da'is Abu Najam Siraj and Momin and begged of Da'i Momin to accept his allegiance on behalf of Hazrat Imam. However, Da'i Momin, who was well conversant with the intelligence and abstinence of Sayyidna Hasan, said: "Though you are Hasan and if I am Momin even then your position is higher than mine. You are in fact very high to the lmam. How am I supposed to take allegiance from you."  Notwithstanding this, upon Sayyidna Hasan's repeated requests, Momin took the allegiance and converted him to Ismaili faith. At that time Sayyidna Hasan was about 35 to 36 years of age.
Tour to Egypt
After embracing Ismaili faith. in 464 A.H. - 1071 C.E. Sayyidna Hasan came into contact with Abdul Malik bin Attash and worked in Da'wat as his assistant for 2 years at Isfahan.  Then Abdul Malik bin Attash asked him to go to Egypt and seek the holy interview of the lmam. Accordingly in 467 A.H. 1074 C E. Sayyidna Hasan left Ray and after travelling for three to four years, reached Egypt in 411 A.H. 1078-9 C.E. and became fortunate to have holy deedar of the Imam, and upon the solicitation of Sayyidna Hasan, lmam Mustansir billah ordered that after him his son 'Nizar' would be his successor. [l6]
Return from Egypt
For about 18 months Sayyidna Hasan remained in Egypt and during this period had the opportunity of seeking several interviews of the lmam. However, by his frequent interviews with the lmam, Wazir Badarul Jamali used to be agitated. By this, he began to breed suspicion and doubts regarding Sayyidna Hasan because Badarul Jamali was from the beginning opposed to Hazrat Imam Nizar. When he came to know that Sayyidna Hasan was the supporter of Hazrat Nizar he became his opponent also and imprisoned him in the castle of 'Dumyat'. By chance some day, a wall of the prison, which was quite strong, collapsed [l7], and it gave chance Sayyidna Hasan to be able to escape. He boarded a vessel at the port of Alexandria and thus in 473 A.H. - 1081 C.E. reached lsfahan, and remained engaged in propagation of Da'wa at Yezd, Kirman, Tabaristan, Damgan in Iran. Then he proceeded to Qazwin and toured the suburbs of the fortress of Alamut. There he remained in prayers and through his preaching converted the natives to Ismaili faith so much their chief also came into Ismaili fold.
Capture of Alamut
There are two versions about the capture of fortress of Alamut.  One is that the possessor of the fortress, Mahdi, the governor of Sultan Malik Shah, belonged to Alvi dynasty. One day Sayyidna Hasan invited him wherein, besides faithfuls of Ismaili concept, other dignitaries of the town were present. Sayyidna Hasan bin Sabbah upon conversing on the service to lmam said that the fortress would be of great value for the service to lmam and there on the spot a bargain of the fortress at the price of 3000 dinars was arrived at. Mahdi thought that Sayyidna Hasan would not be able to pay the said sum of the price. Hence he accepted the bargain. Sayyidna Hasan wrote to Rais Muzaffar of Girdkub and Damgan mentioning the sum, who on receiving the letter immediately remitted the amount. Governor Mahdi, as promised, assigned the fortress to Sayyidna Hasan.
Another version is that Sayyidna Hasan bin Sabbah asked of governor Mahdi for only that much portion of land which would cover the skin of a cow. Governor consented to that. Whilst measuring the land Sayyidna Hasan made the skin into such tiny pieces that it covered the whole fortress. In this way the entire fortress was handed over to Sayyidna Hasan. In any case, in 483 A.H. Sayyidna Hasan got the fortress of Alamut. [l9]
Fight with Saljuqs
When the news of the fortress of Alamut having fallen to Sayyidna Hasan reached the court of Malik Shah, Nizamul Mulk became highly perturbed and despatched several units of army one after another, one of which laid a seige to the fortress for nearly 4 months but to no purpose as it was all in vain. In the mean time in 485 A.H. - 1092 C.E. Malik Shah discharged Nizamul Mulk from the office of Wizarat and got him slain and within a few days time in the same year Malik Shah also expired. His sons quarrelled over the throne continuously for nearly 10 years.
During this lapse of time Hasan found the golden opportunity of propagating Ismaili concept and strengthening his hold, and captured Rudbar, Tabaristan, Khuz, Khosaf, Zozan, Quain and Tune.
However, whenever any of the heirs of Malik Shah used to find any chance, he would dispatch a unit of army against Sayyidna Hasan, but due to the vigilance and dauntlessness of Sayyidna Hasan their attacks were foiled. Eventually Saljuq Sultan Sanjar, made truce with Sayyidna Hasan by which it was agreed upon that any trader passing through Khurasan shall have to pay a tax to Ismailis and on the other hand Ismailis would neither construct new forts nor convert or bring more people into Ismaili Da'wat and faith.  Nevertheless groups of people embraced Ismaili faith without any propagation. In this way reliance upon Sayyidna Hasan began to shine like day's light throughout Iran and Khurasan and high officials of Saijuq Sultan also became Ismailis. 
In short Sayyidna Hasan bin Sabbah, during his life time, achieved his aims like freedom of Ismaili territory, freedom of Ismaili faith and established peace between him and his opponents. By his political and intelligible skill he made the powerful Saljuqi government to come down to terms of freedom for Ismaili politics and concepts.
After having overcome Saljuqs in Iran and Khurasan, Sayyidna Hasan turned his attention towards Syria and India and deputed Da'is there. Upon having spread Ismaili Da'wat in Iran and Syria as well as introducing the Dawa in India, Sayyidna Hasan Bin Sabbah took to reducing his lofty ideas and thoughts in writing. He continued his work pertaining to Ismaili faith and tenets till he breathed his last. Incidentally, in 518 A.H. - l124 C.E. a fatal disease attacked him and he succumbed to it. He was 90 years of age at the time of his death.
Fidai or Assassin
Ismailis of the era of Sayyidna Hasan bin Sabbah were termed to be Fidais of Assassin. The word 'Fidai' is derived from 'Fida' meaning sacrifice. Because Ismailis used to sacrifice, i.e. give away their lives and everything for faith, they are termed as 'Fidais'. But as far as the word 'Assassin' is concerned there is a controversy. Some say it is 'derived from the word 'Hasaneen' meaning followers of 'Hasan', Some say that the word actually was 'Hashish' meaning addict of a green intoxicating herb 'Hashish'. This assumption is founded on their belief that at the time of war to keep up the spirit of his soldiers, Sayyidna Hasan used to drug them with 'Hashish'. But what an illogical belief it is that if a person who has lost his control over self through the drug how can he vouchsafe his defence with sensible strategy, for their valour and intrepidity was specifically in enthusiasm of their faith to which they were attached.
Allegations against Sayyidna Hasan and its refutation
Many allegations are being made against Sayyidna Hasan to the effect that he was blood thirsty and through his 'Fidais' he had made lives of people repressed and unrestful. But all this is totally untrue. His only purpose and meaning of recruiting army of Fidais was to protect Ismailis from the foil and destructive attacks of enemies. The very significant example of this is his human behaviour with Sultan Sanjar. If Sayyidna Hasan wished to, he would not have forgone the opportunity of slaying him, for he only wanted him to get horrified and give up the seige.
One of the allegations against him is that he murdered Nizamul Mulk through one of his Fidais. However, the history itself is a witness to the fact that Nizamul Mulk was murdered by Sultan Malik Shah. There were many reasons for that. One of it is that Sultan was afraid of his increasing powers to his detriments. Another reason is that Malik Shah was already in the influence of Ismaili concept, and he was in contradiction to the vindicative nature of Nizamul Mulk against Ismaili faith.  The third and main reason was that Turkan Khatun, begum [wife] of Malik Shah was deadly against Nizamul Mulk for she wanted her son, Mahmood, to succeed Malik Shah and it was not possible with the deviation of Nizamul Mulk, who had made it clear to Turkan Khatun that son of Malik Shah's cousin Zubeda, Barruk bin Dawood, was to succeed Malik Shah, as he had the qualities of wisdom befitting a ruler and also belonged to Saljuq dynasty. For this Turkan Khatun poisoned the ears of Sultan against Nizamul Mulk and Malik Shah got him murdered and this became the reason of downfall of the famous position of Wizarat and murder of Nizamul Mulk. In the face of this it is absurd and nothing but a false allegation against Sayyidna Hasan bin Sabbah for the murder of Nizamul Mulk. 
The most defamatory allegation against Sayyidna Hasan is that he had created a paradise in the fortress of Alamut. If we consider this allegation also in the light of history, it will prove to be nothing else then a fiction. If such a paradise was at all created by Sayyidna Hasan it would not have remained unaccounted for by the historians. However, no such account is to be found anywhere in Ata Malik Juwayni, who was a historian and a companion of the destroyer of Ismaili reign in Alamut in 654 A.H. - 1256 C.E. i.e. Halaku Khan. He has made no mention of anything of that sort in his book "Tarikh-e-Jahan Gusha". Mention of this paradise is found only in 'the "Travels of Marco Polo", who reached thereafter one and half century of the existence of Sayyidna Hasan bin Sabbah in 673 A.H. - 1273 C.E. and it was no doubt the stories that he had collected without any foundation. But for the welfare and progress of Ismailis Sayyidna Hasan bin Sabbah had created peace, comfort and settled condition in the fortress.
One more allegation made against Sayyidna Hasan is that he was desirous of acquiring political power and strength and for that he had disguised himself in the cloak of Nizari Da'wat. But the history proves that he had no such aims and historians agree that neither he himself had been addicted to alcohol nor did he allow anybody to do so. He killed one of his own sons for accusation of taking alcohol. He intended Ismailis to be as firm in faith as he himself was. He had inculcated the habit of earning their livelihood through hard work and toil and his wife and children and himself were leading a simple life. The effect of this was that his command to faithful was carried out immediately and the glory that credited Sayyidna Hasan is not to be found for anybody else in the pages of history.
'1. Jawad al-Mascati 'Hasan bin Sabbah' (first edition), pg. 38. Published by Ismailia Association in English.
2. Bernard Lewis 'The Assassins' (1967), pg. 38.
3. Encyclopedia of Islam (old edition), pg. 267; W. Ivanow 'Alamut and Lamasar', pg. 20; Syed Suleman Nadvi 'Khayyam' (1933), pg. 56; Bernard Lewis 'The Assassins', pg. 40 & 61.
4. Jawad al-Mascati 'Hasan bin Sabbah', pg. 152; Nizam ul-Mulk Tusi, pg. 447.
5. Rashid ud-din Fazalellah 'Jame-ut-Tawrikh', pg. 1 (in Persian).
6. Nizam ul-Mulk Tusi, pg. 420, foot note No. 3
7. E. G. Brown 'Literary History of Persia', Vol. 11, pg. 201.
8. Syed Suleman Nadvi, 'Khayyam', pg. 38.
9. Syed Suleman Nadvi 'Khayyam', pg. 18; Nizam ul-Mulk Tusi, pg. 48.
10. ncf. Ibn Khallikan, pg. 43, Vol. I.
11. Syed Suleman Nadvi, 'Khayyam', pg. 28.
12. Syed Suleman Nadvi, 'Khayyam', pg. 28.
13. Karim Kishawars 'Hasan Sabbah', pg. 64.
14. Karim Kishawars 'Hasan Sabbah', pg. 64; Nizam ul-Mulk Tusi 'Dihastan ui-Madhhab', pg. 423, foot note, NQ. 2; Nizam ul-Mulk Tusi 'Tadhkar-e-Daulat Shah' pg. 423; Karim Kishawars 'Hasan Sabbah', footnote pg. 72.
15. E. G. Brown 'Literary History of Persia', Vol. 11, pg. 203.
16. 'Tarikh-e-lbn Khaidun', Vol. V, pg. 156.
17. Nizam ul-Mulk Tusi, pg. 425.
18. Ali Mohammedd Jan Mohammedd Chunara 'Noor-e-Mubin', pg. 366 (first ed. in Urdu).
19. Nizam ul-Mulk Tusi, pg. 428.
20. Jawad al-Muscati 'Hasan bin Sabbah', pg. 150.
21. Jawad al-Muscati 'Hasan bin Sabbah', pg. 150.
22. Jawad al-Muscati 'Hasan bin Sabbah', pg. 141.
23. Nizam ul-Mulk Tusi, pg. 149.
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