The quaternary Cs2S/Bi/As/S system was studied in an attempt to introduce two different asymmetric but isoelectronic building units, namely, [(BixSy)-S-III] and [(AsxSy)-S-III], in a single structure. Reactions with a comparatively lower equivalent of arsenic in the Cs2S/Bi/As/S mixture led to the crystalline compound Cs3Bi(AsS4)(2). The structure features tetrahedral [(AsS4)-S-V](3-) connected to Bi-III centers to give infinite 1/infinity[Bi(AsS4)(2)(3-)] chains. When the basicity was raised in these low arsenic fluxes by increasing the Cs2S fraction, the crystalline compound Cs9Bi(AsS4)(4), also featuring [(AsS4)-S-V](3-) anions, was formed. On the other hand, arsenic-rich mixtures of Cs2S/Bi/As/S led to the formation of the glassy phase Cs2BiAs3S7, which contains As-III species. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and pair distribution function (PDF) analysis indicate the presence of As-III-containing [AsnS2n+1] fragments in the glass structure. Several glasses in the series Csn-1BiAsnS2n+1 were also prepared using solid-state fusion reactions. The band gaps of the Csn-1BiAsnS2n+1 glasses are in the range of 1.51-1.81 eV, while that of the crystalline compound Cs3Bi(AsS4)(2) is similar to 2.33 eV. The thermal and optical behaviors of these compounds are correlated with their structures and building units.