Green’s Dictionary of Slang

(US black) a fellow black person; also as adj.

1967		A. Baraka Tales (1969) 24: There’s not really much work around for spliv actors.
1972		K. Johnson ‘Vocab. of Race’ in Kochman Rappin’ and Stylin’ Out 148: Spliv or Splib. Can be pronounced either way.
1995		S. Moore In The Cut 98: I have new words for the dictionary. [...] spliv, black person.