Simplify the following text for a Grade 6 native English-speaking person.
Original: The Treaty was concluded between Ramesses II and HatusiliÅ III in Year 21 of Ramesses ' reign . ( c. 1258 BC ) Its eighteen articles calls for peace between Egypt and Hatti and then proceeds to maintain that their respective gods also demand peace .
Simplified: The treaty was made in year 21 of Ramesses ' reign , probably 1258 BC .