What did they rap about in the 1970s ??

hip-hop

The most common view that is seen, is that hip-hop is a cultural movement that emerged in the South Bronx in New York City during the 1970s, with MCing (or rapping) being one of the primary four elements.

Explanation:

Ice Ice Baby (Official Music Video) Vanilla Ice

Explanation:

Hip hop as both a musical genre and a culture was formed during the 1970s when block parties became increasingly popular in New York City, particularly among African American youth residing in the Bronx.

i believe it is a. a segment : )