This paper presents original field work data from the Bassila variety of Anii. We provide the first description of the Anii negation system and its interactions with indefinite noun phrases. We further analyze this apparently bipartite system as one in which a semantically negative preverbal particle obligatorily co-occurs with a postverbal negative focus marker, which does not itself contribute a semantic negation. We discuss the implications of this for our broader understanding of bipartite negation and the typology of negation systems more generally, suggesting a close relationship between focus and negation in systems such as the one found in Anii.