Manisha ji
Many of the bhagats would not have known Guru Nanak Dev ji. Your question is very interesting. And, it does not have a short answer.
You are right when you say that their banee was included in Sri Guru Granth Sahib Maharaj by Guru Arjan Dev because they preached the same principles found in Guruji.
Some of the bhagats lived and died before the birth of Guru Nanak, and therefore they lived and died before the life of Guru Arjan Dev, who compiled the Adi Granth and included their banee. So to start the answer I am posting the list of the Bhagats. Bhatts are not included. The Bhatts for the most part lived during lifetime of Guru Ram Das and Guru Arjan Dev and were Hindus. So here is the list. The dates for birth and death are not given for each bhagat, probably because that is difficult to pin down with accuracy.
I am using the birth and death of Guru Nanak to give a baseline (15 November 1469 – 22 September 1539) because if a bhagat died before Guru Nanak was born, then he would not have had contact with Guru Nanak, or any of the other Gurus.
You can Google their names and find out the dates for birth and death if any are missing.
The Bhagatas: Saints of various faiths Sri Guru Granth Sahib Ji Maharaj - sikhee.com Bhagat Kabir: 534 hymns: Kabir (1398 to 1495) was raised by a Muslim mother. Kabir was a proponent of the Bhakti movement. He lived as a householder, abhorred the caste system and religious rituals. He was an saintly apostle of peace, love and unity and a great poet. Kabir believed in inward purity, and was respected by both Hindus and Muslims.
Bhagat Kabir ji died before Guru Nanak was born.
My note: Kabir ji did not become a follower of Guru Nanak, although there is evidence that he and Guru Nanak were in contact with one another. Bhagat Sheikh Farid: 123 hymns: Sheikh Farid (1175 to 1265) was a Muslim Sufi saint of great piety. He is considered the father of Punjabi poetry. He was greatly loved for his kindness and humanity. He stressed living a simple yet purposeful life concentrating on One God.
Sheik Farid died before Guru Nanak was born. Bhagat Namdev: 62 hymns: Namdev (1270 to 1350) was a celebrated saint from Maharashtra who traveled extensively across the country. He lived in Punjab for a number of years.
Bhagat Namdev died before Guru Nanak was born. Bhagat Ravidas: 40 hymns: A contemporary of Kabir and a disciple of Ramanand, Ravidas represents the culmination of the Bhakti Movement. He came from a low caste cobbler family but had many disciples because of his spirituality. He stressed a life of simplicity and piety.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=30937 Bhagat Trilochan: 5 hymns: A contemporary of Kabir and a celebrated Sain of the Vaish caste. He believed in One God and condemned superficial rituals and stressed the holiness of the heart.
As a contemporary of Kabir ji, Bhagat Trilochan may have encountered Guru Nanak. Bhagat Beni: 3 hymns: Probably a contemporary of Namdev, not much is known about him. He was unperturbed by poverty and enjoyed a life of solitude enriched by his spiritual per suits. He was a great scholar as is evident from his writings.
Bhagat Sheikh Bhikan: 2 hymns: A Muslim Sufi scholar saint Sheikh Bhikan died in the early part of Akbar's reign. He was one of the most learned men of his time. He believed that only God's name can heal a diseased mind and body.
Akbar lived from 1556-1605 and this also overlaps nearly exactly with the life of Guru Arjan Dev. Therefore Guru Arjan Dev may have had encounters with Bhagat Bhikan. Bhagat Dhanna: 4 hymns: Dhanna was a Jat from Rajasthan who was born in 1415. He lived most of his life as an idol worshipper but in later years became a worshipper of One God and renounced all superstitious practices.
Bhagat Dhanna may have lived during the same time as Guru Nanak, but would be 54 years older than Guru Nanak. Bhagat Jaidev: 2 hymns: Jaidev was a renowned poet laureate in the royal court of king Lakshman Sen of Bengal. His famous work of poetry Gita Govinda is well known for its poetic beauty and musical richness.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=30937 Bhagat Paramanand: 1 hymn: Born in Maharashtra, little is known about Paramanand's life. It is believed that he lived in Maharashtra and was a devotee of Krishna. He later became a proponent of One God.
Bhagat Pipa: 1 hymn: Born in 1425, Pipa was the king of the princely state of Gagaraungarh. He abdicated his throne, traveled extensively and became a disciple of Ramanand. He lived a life of extreme austerity and humility.
Bhagat Pipa may have lived at the same time as Guru Nanak. He wold have been born 44 years before Guru Nanak.
Bhagat Ramanand: 1 hymn: Ramanand, a Brahmin
was born in 1359 in Madras. He is regarded as the pioneer of the Bhakti movement in northern India. A Vaishnava in his early life, he became a worshipper of Brahm and condemned the caste system. Kabir was the most renowned amongst his disciples.
Bhagat Ramanand would not have lived at the same time as Guru Nanak. He was born 90 years before Guru Nanak. Bhagat Sadhna: 1 hymn: A butcher by profession, Sadhana was born in Sind. His piety and meditation of God elevated him to saintly status. He was condemned by Brahmins and on a false charge was arrested and buried alive.
Bhagat Sain: 1 hymn: Sain was a barber of the royal court of Raja Ram, king of Rewa. He was a follower of Ramanand and Kabir.
Bhagat Sain was a follower of Kabir, so he may have indeed lived at the same time as Guru Nanak. However no dates are given for the birth and death of Bhagat Saini.
Bhagat Surdas: 2 hymns: Surdas was a Brahmin born in 1529. He was learned in Sanskrit and Persian and studied music and poetry. He was appointed a governor by emperor Akbar, but was later imprisoned for dereliction of duty. Towards the end of his life, he became a hermit and lived among holy men.
Bhagat Surdas was born 10 years before Guru Nanak died, and Guru Nanak would have been 70 years older than Bhagat Surdas.
Bhai Mardana: 3 hymns: Mardana was a rabab (rebeck) player who spent most of his life as a disciple and musician of Guru Nanak. Born a Muslim, Mardana was a childhood friend of Guru Nanak and accompanied him on all his great travels.
Bhai Mardana was a boyhood friend of Guru Nanak and they spent their entire lives together. Satta & Balwand: 8 hymns: Satta was a rebeck player who served Guru Angad, Guru Amar Das, Gur Ram Das and Guru Arjun Dev. Along with his fellow musician Balwand they jointly composed a ballad which appears in the Guru Granth Sahib.
Not clear if Satta and Balwand were contemporaries of Guru Nanak, but they did live their lives at the same time as Guru Amar Das, Guru Ram Das, and Guru Arjan Dev. However without dates it is not clear. Bhagat Sunder: 6 hymns: Baba Sunder (1560-1610) was the great grandson of Guru Amar Das. His composition called Sadd (Calling) was written at the request of Guru Arjun Dev after the death of Guru Ram Das.
Bhagat Sunder was born after the death of Guru Nanak. It is interesting to look at his birth and death dates, because they overlap very closely with the birth and death of Guru Arjan Dev. 15 April 1563 – 30 May 1606. He would not have had contact with any of the Gurus before Guru Arjan Dev.
Many, though not all, of the bhagats whose lives overlapped with Guru Nanak, and Gurus Angad, Guru Amar Das, and Guru Ram Das were Hindus and I do not know if they abandoned Hinduism to follow Sikhi.
If you go to this web site -
sikh[/B]-history.com/
you can get more details about each of t.he bhagats. Maybe you can fill in the m issing dates for some of the one's I missed. I hope I gave you enough information to start on your investigation, answer your quesiton.
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