Sources of Sikh history 
Dr, Harjinder Singh Dilgeer
Though the Sikh religion is only five hundred years old but the Sikhs have not produced any authentic work so far. There have been three trends of the writers of Sikh history: 
1. Those who wanted to distort the religion of the Sikhs and their history. 
2. Those who wrote books with limited information or with material from faulty sources. 
3. The over enthusiastic Sikhs who wanted to present Gurus as men of occult power, showing miracles and acting as if they were incarnation of God. 
Hence, all these works were supposed to be partial or defective. But, still people of impartial mind and sharp intellect can separate grain from chaff and understand the truth of the Sikh history and philosophy.
Among the Gurmukhi and Punjabi sources, the best one are the Bhatt Vahis (literally: registers of the Bhatts); the Bhatts used to record the births, marriages, battles, deaths of their ‘clients’; hence, these are the genealogical account of prominent Sikh clans, mostly Rajputs and Khatris. The Bhatts were their family priests commonly called purohits; however, it is not proper to call them priests; they were a sort of record-keepers. As the Bhatt Vahis had been written by the Brahmins, hence they had presented the material with exaggeration and might have concocted some stories also. But, their preservation of the record of dates, names of people and places and other data is the most precious treasure of history of their times (and only this part of the Bhatt Vahis should be used). 
The most authentic source of the Sikh history is Guru Granth Sahib. This is not a work of history but there are some references to some events in this Granth: it depicts, e.g. the scene of the destruction caused by Babar in Sayyadpur (Eimanabad) in 1520; the assessment of the role of Bhagt Ravidas, Bhagat Kabir, Bhagt Namdev etc; the scene of death of Guru Amar Das; the role of Guru Sahibs etc (by Satta & Balwand and Bhatt poets).
Similarly, another work of probably 1698, Bachitar Natak, also preserves some precious information. It is (wrongly) attributed to Guru Gobind Singh, and, it is a writing by one of the poets who had been living at Anandpur and Paonta. Like several other mythological and hagiographic works, the first part of this book too, is just fiction. It seems its author was a Brahmin who wanted to present Guru Gobind Singh as a part of the Hindu mythological stream; but, the second half of this work, covering the period from 1675 to 1698, is precious history. It narrates the battles of Bhangani, Nadaun, Guler with fine details; and, the data presented in this part is accurate and is also corroborated by other contemporary works. (It is possible that the first part might have been written much later and then compiled into one work by some cunning Brahmin).
The next work is Gur Sobha written by Sainapati in 1711. This work covers the period between 1698 and 1709. This is the best work about the life and time of Guru Gobind Singh; though it does not present a lot of information. It is from this work that we learn about the revelation of Khalsa, the role of the Hindus with regards to the Sikhs; the code of conduct given by the Guru for the Sikhs. This is the first objective work of history of that period.
Another precious source is the hukamnamas. Shamsher Singh Ashok and Dr Ganda Singh collected and published a volume of such hukamnamas but, an analysis of the wording of these hukamnamas proves that most of these are fake, and probably were got prepared by some people to establish their importance as well as money in the form of offerings.
It is likely that most of them were created during the period of the rule by the Misls or Maharaja Ranjit Singh who might have patronized those who claimed to have ‘received’ these ‘relics’.
The second stage of sources is the Gurbilas literature (biographies of the Gurus) which was composed in the second half of the eighteenth century or in the first half of the nineteenth century. They are replete with fiction and hagiographic material besides several concocted stories, thus distortion of history. Three such works are often quoted by some writers: Gurbilas Patsahi 10 (1751) by Koer Singh, Gurbilas Patsahi Dasvin (1797)  by Sukha Singh and Gurbilas Patsahi Chhevin (1835-40 and not in 1718 as mentioned in one stanza of this book) by some unknown author (by Gurmukh Singh and Darbara Singh, as per Kahan Singh Nabha). It seems that the authors of these works were Nirmala-Brahman people who deliberately distorted the history.
Koer Singh’s work (Gurbilas Patsahi Dasvin 10) claims to have been compiled in 1751. This big volume of 2938 stanzas is mainly the life of Guru Gobind Singh. The author has narrated the scene of revelation of Khalsa, Guru’s journey from Anandpur to Talwandi Sabo (5.12.1705 to 16.1.1706), martyrdom of the Guru at Nander (October 1708), grant of Gurgaddi to Guru Granth Sahib (6.10.1708) and martyrdom of Bhai Mani Singh (24.6.1734) and some other events in much detail. There are several incorrect details in this work. The author claims that he had got information from Bhai Mani Singh when the latter was in jail from April to June 1734, and, he (Koer Singh) was a jailor at Lahore. This too is false as it was impossible that during those days a Sikh could have been appointed to such an office. 
It seems that Koer Singh concocted this in order to give importance and credibility to his work. It is likely that Koer Singh had read Bachitar Natak and Gur Sobha as his depiction resembles the presentation made in these
works.  
Sukha Singh (Gurbilas Patsahi Dasvin) was a Granthi at Patna. Though a Sikh by name he seems to be a more of a Hindu, that is why this work is full of Pauranic fiction, hagiographic stories, gossips, miracles and other fiction; hence distortion of Sikh philosophy and history. This author even himself wrote some books and preached them as the writings of Guru Gobind Singh (which were, later, compiled as Dasam Granth).        
Kesar Singh Chhiber (great-grandson of Diwan Dargah Mall, minister of Gurus from 1644 to 1696) wrote Bansawalinama Dasan Patsahian Da in 1769. Kesar Singh was the great-grandson of Diwan Dargah Mall, who had been the Diwan (minister) under Seventh to Tenth Gurus. Bhai Mati Das and Sati Das were his collaterals. His father Gurbakhsh Singh was the Daroga (a senior official) for the city of Amritsar for some time. The first half of this work (covering the period from Guru Nanak to Guru Arjan Sahib) presents very precious information about events of Gurus’ period (births, marriages, deaths, geneology etc), which is not available from any other source; it is so accurate and up to date that it seems to be based on some original records; it seems that he had in his possession the real “Janamsakhi Bhai Bala’ with him. But, the second part of this book is based on author’s memoirs; hence defective information. In 1790, Swarup Singh Kaushish wrote Guru Kian Sakhian, which was solely based on Bhatt Vahis.
This book has very precious data of the Guru-period. The writers of these records were Brahmins and belonged to the priestly profession; hence they have presented the details with a tinge of Brahmanism but even this mingling of Sikhism and Brahminism is not so dangerous as that by the writers of Gur Bilases. In spite of this, Bhatt Vahis and Guru Kian Sakhian is a great treasure of the dates of events, the places associated with these events as well as the names of the Sikhs of that time etc. Other works based on the Bhatt Vahis include Guru De Sher (2001), Mata Gujri Char Sahibzadey Chalih Muktay (2005), Bhai Mani Singh Tay Unhan Da Parvar 2010), all three by Dr Harjinder Singh Dilgeer. 
Almost of the same period is precious work Shaheed Bilas (edited and published by Giani Garja Singh in 1961). Though this is the biography of Bhai Mani Singh but it contains very precious information about the period from seventh to tenth Guru and even up to 1734.
Major of the distortion of Sikh history began with Sarup Das Bhalla who wrote Mahima Parkash in 1776. This work was in prose (prose work has been edited by Dr Kulwinder Singh Bajwa) and it was presented in poetry by Budh Singh in 1840. This work was first to distort history by concocting gossip stories, including that of the so-called Tat Khalsa and Bandai Khalsa.
A work by Kavi Sondha, Hatim Nama (1809) gives details about the ten Gurus; but this work is full of incorrect information. In the same period Sumer Singh Bawa wrote Guru Pad Prem Parkash which too is full of incorrect information; probably both of these were based on hearsay information. Sukhbasi Rai Bedi’s Guru Nanak Bans Parkash and Veer Singh Bal’s Singh Sagar too can also be considered works of the same pattern.
The next in this series are the nineteenth century works, including those by Santokh Singh (Gur Partap Suraj Granth, 1839), Ratan Singh Bhangu (Prachin Panth Parkash, 1814/1840) and Giani Gian Singh (Panth Patkash 1890). Though, these books are chronological account of the Sikh history but all the three are replete with seriously distorted information. However, another work Shashi Bans Binod (1879) by Ganesha Singh Bedi has preserved some precious data of relations between the Gurus and the Bilaspur state Bedi’s another work Guru
Bans Binod, though small in size, too preserves important information).
Hutchison and Vogul based their book History of the Hill States partly on this work too. Ram Sukh Rao’s Fateh Singh Parbhakar and Jassa Singh Binod (written in the second half of the nineteenth century) too have some useful information. Amritsar Di Vaar by poet Darshan too is an important work. Several more Vaars too were produced during this period and these are replete with data about the battles of Guru Gobind Singh; these Vaars have been edited by Piara Singh Padam in the work Punjabi Vaaran.
Dr Gopal Chand Barua published his book Assam Barunji (1930), based ont Assame records and this work has some precious information about Gru Tegh Bahadur’s vist to Assam.
Persian sources too are valuable source of information about the Guru period; reference to the Gurus too can be found in Akbar Nama (Abu Fazal, 1601), and Tuzk-i-Jahangiri (1620s) but Dabistan-i-Mazahib (1645-46) by Zulfikar      Ardastani (earlier mistaken as Muhsan Fani) has much detailed information about Sikhism (though it is an amalgam of right information and hearsay material).
Sujan Rai Bhandari’s Khulastut Twareekh (1696) also has some references to Guru-period but it covers the period up to 1695-96 only.
Akhbarat-i-Darbar-i-Mu’alla(literally: the news of the court of the emperor); this is in the form of the reports sent by the agents of Jaipur state (who used to be in the Delhi Darbar, as well as in the company the troups of the Mughal Emperors). From this source, one can read daily diary of the events of the period 1707 onwards (till 1750s). These records have a couple of references to Guru Gobind Singh.
Other writings of the nineteenth century include: Ahiwal-i-Twareekh-i-Punjab (unknown author, 1806), Kitab-i-Twareekh-i-Punjab (Khushwaqt Rai 1812; he was the vakil of the English in Lahore Darbar), Umdatut Twareekh (Sohan Lal Suri is daily diary of the peiod 1812 to 1840), Tareekh-i-Punjab (Ahmed Shah Batali, c 1849), Tareekh-i-Punjab (Bute Shah, 1848), Char Bagh-i-Punjab (Ganesh Das Vadehra 1849), Ibrat nama (Ali-ud-Din) etc were mostly written under instructions from the English regime; hence it is likely that these works were written with a purpose (including distortion of history).
A large number of the Persian sources were translated into English by Elliot and Dowson in their 8 volume production History of India as told by its Historians (1877). But, the translation by these authors is not free from mistakes. 
In 2001 J.S. Grewal and Irfan Habib Published Sikh History from Persian Sources but in this volume too the authors have presented a partial picture. Dr Ganda Singh too ad published selected portions of Persian works under the heading of Makhaz-i-Twareekh-i-Sikhan. 
Persian sources have been used by Karam Singh Hisotrian, Dr Ganda Singh, Dr Hari Ram Gupta, Dr Fauja Singh and Dr Bhagat Singh too.  
In 1906 Nur Ahmed Chisti wrote Tahqiqt-i-Chisti which is full of useful information.
In nineteenth century Charles Wilkonson’s The Sikhs and their College at Patna and John Malcolm’s Sketch of the Sikhs (1809) were written with a purpose; hence propaganda literature and deliberat distortions. General J.D. Cunningham wrote the first formal history of the Sikhs in 1848. This book contains precious information about the Anglo-Sikh Wars but the earlier part about the Gurus is shockingly incorrect and distortion, though because of lack of information with the author.