What was the first form of hip hop?

In the 1970s, an underground urban movement known as "hip hop" began to form in the Bronx, New York City. It focused on emceeing (or MCing) over house parties and neighborhood block party events, held outdoors.

Explanation:

DJ Kool Herc started hip hop

Hip Hop in the 70s

For the first time, DJ Kool Herc started creating such tracks. In 1970, his followers merged into the first hip-hop label - The Sugar Hill. However, 1979 is considered the official year of hip-hop formation, when the first full-fledged composition in this style was released - Rapper's Delight.