This question previously had details. They are now in a comment.
Kulveer Singh (कुलवीर सिंह), I write on unknown heroes of Sikh history
Updated Jan 18, 2018
Originally Answered: Was Sikhism formed to protect Hindus in Punjab from the oppression of Islamic invaders?
There is no unipolar or simple answer to this question. The answer cannot be restricted to the established dogmas and straitjacket prevailing definitions. It needs to dwelve into the evolution in short.
All religions start as movements that point out social ills that have developed in religious traditions over time; and to show a new path to spiritualism. And so did Sikhism.
Guru Nanak Dev ji started his lectures and his spiritual tours in that tradition; propagating a humane and spiritual version of religions, while pointing out flaws that had developed in Hinduism as well as Islam over time. His Baani also has a large amount of metaphysical and spiritual interpretation of the manifestation of God and his creations; about the concept of the world being a Maya and the ways to break the cycle of Maya and assimilate into the one omnipotent, omnipresent God; the Ek Omkaar.
Gurus that followed him, followed his tradition; but after the killing of the fifth Guru by Jahangir, there was a clear movement towards training and arming themselves for conflicts under the Sixth Guru, Guru Har Gobind ji. Guru Har Gobind for the first time (to the best of my knowledge) gave importance to Physical Strength (and warrior qualities) with his concept of twin swords of Miri-Piri (Miri signifying Physical/Material Strength and Piri signifying Spiritual Strength)
One must understand that in the records of Jahangir or Aurangzeb’s contemporary accounts; the Sikh Gurus are mentioned as Hindus. So, there was no clear-cut distinction between Sikhism and Hinduism till the arrival of Guru Gobind Singh.
With the arrival of the tenth Guru, Guru Gobind Rai, who later became Guru Gobind Singh ji; Sikhism took a firm identity of Khalsa, with the five Kakars. What we see as Sikh ideology or Sikh identity today is a result of the creation of the Khalsa identity.
On Baisakhi Day in 1699, a congregation of people from across India were standing listening to their Guru, Gobind Rai. Gobind Rai Ji asked for human sacrifice of five men one after the other. Five men from different castes from different parts of the Indian Sub-Continent stood up from a crowd of thousands.
– A shopkeeper Baniya called Daya Ram from Lahore
– A farmer Jat called Dharam Das from Meerut
– A so called low-caste water carrier called Himmat Rai from Jagannath Puri, Odisha
– A tailor of Cheemba caste called Mukham Chand from Dwarka, Gujarat
– A barber of Naai caste called Sahib Chand from Bidar, Karnataka
These five people from five strata from five parts of India represent the first five disciples, and were called the Panj Pyaras (the five beloved disciples of the Guru); all of them erstwhile Hindus.
Guru Gobind Singh Ji in Sarbloh Granth has written that he gave his disciples the ‘Swaroop’ of a Muni (Munis/Rishis – ancient spiritual ideologues – had head buns on their heads, what we call the ‘Jooda’ now) and the Power of a Soorma (Brave Warrior); to spread the rule of law and righteousness from the oceans to the mountains; thus taking the concept of Miri-Piri further. The Sarbloh Granth describes the creation of the Khalsa as follows:
ਅਕਾਲ ਪੁਰਖ ਕੀ ਆਗਯਾ ਪਾਇ, ਪ੍ਰਗਟਿ ਭਯੋ ਰੂਪ ਮੁਨਿਵਰ ਕੋ ॥
Akaal purakh ki agya paayi, pargati bhayo roop munivar ko ||
By the command of Akal Purkh, [the Khalsa was created] with the form of [sacred] Muni’s.
ਜਟਾ ਜੂਟ ਨਖ ਸਿਖ ਕਰ ਪਾਵਨ, ਭਗਤ ਸੂਰ ਦ੍ਵ ਰੂਪ ਨਰਵਰ ਕੋ ॥
Jataa jut nabh sikh kar paavan, bhagat soor dwa roop narwar ko ||
With the long hair from the topnot to the nail of the toe, like a Muni, and the form of both a devoted worshipper [bhagat] and warrior [soor/ soorma].
ਚਕ੍ਰਵੈ-ਪਦ ਦਾਤ ਧੁਰਿ ਪਾਯੋ, ਧਰਮਰਾਜ ਭੁੰਚਤਿ ਗਿਰਿਵਰ ਕੋ ॥
chakwaye-pad daat dhhuri paayo, dharamraj bhunchti giriwar ko ||
The ‘Chakarvarti Raj’ [Kingdom which is victorious wherever the Army is present] has been given by the Lord, not even Dharamraj has been given such a high status
ਉਦਯ ਅਸਤ ਸਾਮੁਦ੍ਰ ਪ੍ਰਯੰਤੰ, ਅਬਿਚਲ ਰਾਜ ਮਿਲਯੋ ਸੁਰਪੁਰ ਕੋ ॥੪॥
Uday asat samud prayunt, abhichal raj milye surpur ko ||4||
From where the sun rises to where it sets, across all the oceans, [The Khalsa] has received the timeless Raj [kingdom] from Sachkhand
As a result of this new identity, hitherto passive stratas of society threw away their inaction and took their destiny into their own hands. It was then that then Guru Sahib said his now famous words:
Chirion se main baaz ladaawa, Tabe Gobind Singh naam kahawa
(It is when I make sparrows fight hawks that I am called Gobind Singh)
Gidderon se main sher banawa, Tabe Gobind Singh naam kahawa
(It is when make I lions out of jackals that I am called Gobind Singh)
Nichon se main ucch banawa, Tabe Gobind Singh naam kahawa
(It is when I make the lowly rise that I am called Gobind Singh)
Sawa lakh se ek larawa, Tabe Gobind Singh naam tharawa
(It is when I make one fight a lac that I will call myself Gobind Singh)
Hindus had earlier left the duty of fighting to the Kshatriyas. Inspired by such words, even the Banias, Jats, Brahmins and other strata of society combined their forces, and united under the Sikh flag to fight oppression. The so-called sparrows were now brave enough to fight the eagles, under the inspiration of that ideology.
It can be said that:
1 Till the advent of the sixth Guru of Sikhs; Sikhism was about a new way to find God, as with all other religions; but it had not yet acquired a warrior like quality.
2 Khalsa Identity of Guru Gobind Singh Sahib was largely adopted by erstwhile Hindus barring a few conversions from Pakhtoons and non-Indian tribes too.
3 Any fight by Sikhs during or after Guru Gobind Singh Ji was against the oppression of the masses, most of the masses being Hindus and most of the oppressors being Muslims. So their fight was not to protect a third person or ‘others’; but to protect their own kith and kin. There were cases where the elder son of the family was a Sikh and the rest maintained their Hindu identity.
4 It may be said that if the oppressors were not Muslims, the Sikhs would still have taken up arms against injustice. The fight was not a war between religions, but was a war against oppression. This being said; non-muslims being oppressors is just a theoretical assumption. Historically, we know that the scale of oppression done under the flag of Islam was unprecedented, and such mass scale killings and/or conversions never happened under non-muslim rule. The reality was that the fight was against the virulent violent strain of islamic ideology.
5 Sikhism evolved into a separate religion gradually and later firmly established itself as a force to reckon against tyranny. The Sikh identity was thus cemented in conflicts and is now forever tied as a ‘spiritually inclined warrior race’.
6 The Sikhs did uproot Islamic rule from the entire Punjab area, and at one point their area of power spanned from Trans Yamuna to the Khyber Pass.
It can thus be surmised that Sikhism was a sign of resurgence of Hindu masses under a new ideology, leaving aside caste identities, forming the identity of the Bhakt-Soorma (the spiritual warrior) and each person taking their destiny into their own hands.
 Miri piri – Wikipedia
 The Five Ks – Wikipedia
 Guru Gobind Singh’s vision of India
 SikhiWiki, free Sikh encyclopedia.
 Ancient references of the Sikh Jooda
10.3k views · View Upvoters · View Sharers · Answer requested by Duke Singh