What if the 1970s had a hip-hop sub-genre?

Usually, when we think of timeless music genres, we think of genres such as rock, pop and rap. However, while some 1980s rap was released during the end of the 1970s, there isn't really a 1970s rap subgenre. The concept of 1970s rap feels so natural, as a basic genre applied to a famous decade. I personally picture 1970s rap to have been the third of disco and funk, considering how it was influenced by them, but what do you guys think?