Nanak was born in 1469 CE, in a village,00 about 40 miles from Lahore called Talwindi. In honour of Guru Nanak, the town was renamed to Nankana Sahib.
Nanak worked in a government office (now called an accountant). Most of the people in the office were Muslims. Nanak enjoyed talking about beliefs with them, and he learned a lot about Islam and Hinduism.
I was with God!
You shall be the next Guru
Nanak got married when he was 19. He had a wife and 2 sons. It seemed that he had everything he could want.
Nanak went to bathe in the river as usual. But, then he disappered for 2 days. People thought he had drowned. He reappeared on the 3rd day. The first thing he said was 'There is neither Hindu nor Muslim'.
Nanak claimed to have been with God. He had a vision that just following a religion. Doing what the religion said or going on pilgrimages or making offerings does not make a person religious. What really matters is the way they live their life. Nanak said that he had been told by God to spend the rest of his life teaching.
In 1539, just before Guru Nanak died he chose one of his closest followers - Lehna - to be the next Guru. He gave him a new name, Angad, which means 'part of me'.