Simplify the following text for a Grade 10 native English-speaking person.
Original: Guru Nanak ( , , GurÅ `` NÄ nak ) ( 15 April 1469 â `` 22 September 1539 ) was the founder of the religion of Sikhism and the first of the ten Sikh Gurus .
Simplified: Guru Nanak Dev ( October 20 1469 in Nankana Sahib , Punjab , Pakistan â `` September 7 1539 in Kartarpur , Punjab , India ) was the founder of Sikhism , and the first of the ten Sikh Gurus . There are ten Gurus who are important to Sikhs .