Simplify the following text for a Grade 6 native English-speaking person.
Original: In the late 1960s and 1970s , Shines toured with Robert Johnson 's stepson , Robert Lockwood , Jr. as the last remaining original delta blues musicians .
Simplified: In the late 1960s and 1970s , Shines played with Robert Johnson 's stepson , Robert Lockwood , Jr. .