Me, the bard out of work, the Lord has applied to his service. In the very beginning he gave me the order to sing his praises night and day. The Master summoned the minstrel to his True Court. He clothed me with the robe of His true honour and eulogy. Since then the true Name had become my ambrosial food. They, who under the Guru's instruction, eat this food to their satisfaction, obtain peace. By singing the Guru's hymns, I, the minstrel spread the Lord's glory. Nanak, by praising the True Name I have obtained the perfect Lord.

(From A Sikh religious Text by Guru Nanak)

Sri Guru Nanak, one of the founding leaders of Sikhism, was born in 1469 in Talwandi, a village near Lahore, in the present day Pakistan. His father was the village officer of the rural area where Nanak was born . As a boy, he learnt Persian and Arabic as part of his formal schooling. He was married in 1487 and was the father of two children.

1496 is believed to be the year of his enlightenment. After the enlightenment he spent twenty five years preaching and spreading his religious ideas in North India and Pakistan. most of his hymns were composed during this period.

Guru Nanak had a unique sense of his prophethood, which was different from the other Indian spiritual leaders of the time. He always believed that his mission was God-ordained. During his preachings, he used to announce- "As the words of the Lord come to me, so do I express them." Desciples of Guru Nanak have also made similar statements indicating that they were the messengers of god.

Most of his lectures and teachings were in Punjabi, the spoken language of Northern India. The reason for not choosing Sanskrit as the medium might be that he wanted his ideas to be conveyed to the masses, not only to the elites. Sanskrit, the religious language of the Hindus was considered to be a language of the elite class. Later, most of the religious works of the Sikhs were written in Panjabi.

Guru Nanak left the world to eternity On September 22, 1539. It's told that when his followers lifted the sheet covering the corpse, they found fresh flowers instead of the body. The Hindus took theirs and cremated them, while the Muslims took their flowers and buried them.


Sources:

ww.sikh-history.com/sikhhist/gurus/nanak1.html
http://www.sikhs.org/guru1.htm