Simplify the following text for a Grade 16 native English-speaking person.
Original: Some of the main reasons that the Provisional IRA was founded in December 1969 and provisional Sinn FÃ in was founded in January 1970 , was that people like Ã `` BrÃ daigh , O'Connell , and Billy McKee wanted new political bodies and did not want to work in or with the existing bodies such as the Parliament in London .
Simplified: One of the reasons that the Provisional IRA and provisional Sinn FÃ in were founded , in December 1969 and January 1970 , respectively , was that people like Ã `` BrÃ daigh , O'Connell and McKee opposed participation in constitutional politics .