Simplify the following text for a Grade 9 native English-speaking person.
Original: At this time , many European immigrants , especially Italians , moved to SÃ # o Paulo to work at the big coffee plantations .
Simplified: SÃ # o Paulo is the most ethnically diverse city in Brazil . At the end of the traffic of enslaved Africans in the country ( 1850 ) , SÃ # o Paulo started to replace the African manpower with immigrants in the coffee plantations .