South African police have arrested 20 people suspected of instigating the riots that swept parts of the country in July last year.
About 350 people were killed in the unrest that erupted after former president Jacob Zuma was jailed for contempt of court.
Special co-ordinated police raids took place in six provinces, in an operation which relied on extensive trawls through social media posts to pinpoint suspected agitators.
Those arrested are due to appear in a court in Durban on Friday.
An inquiry earlier this year blamed the violence on faceless masterminds, but also heavily criticised the police response.