Before the Civil War, there were no black deaf schools in the South, for obvious reasons. There was no formal education for black people in the South, and that included black deaf people. But after the Civil War, we started to see the emergence of schools for black and deaf people.
The war ended in 1865. It still took until 1869 for a school for black kids to be opened in Raleigh, as a matter of fact. Louisiana didn't even have a school for black deaf kids until 1938, and then it took them until 1978 to desegregate. We had about 18 black deaf schools, even one here in Washington, D.C. Where there was segregated education, due to segregation here in America, we saw the emergence of a different language.
The way their language developed in those schools was varied. They became very innovative with signs, creating vocabularies, creating ways of signing, and ways of expressing themselves.