In this study, a new chalcohalide glass system, Ga2S3-Sb2S3-CsI, is reported. It has a glass-forming domain composed of similar to 0-35 mol% Ga2S3, similar to 15-95 mol% Sb2S3, and similar to 0-55 mol% CsI. The glasses have a wide transparent window of similar to 0.7-13.5 mu m, high third-order nonlinear refractive indices of similar to 1.7-8.7x10(-14) cm(2)/W @ 1.55 mu m, and relatively short zero group-velocity-dispersion wavelengths of 3.8-5.15 mu m. The glasses can dissolve more than 2 mol% active ions (e.g., Dy3+), and the doped glasses show intense emissions in the mid-infrared. These superior properties demonstrate their good potentials for mid-infrared applications such as thermal imaging, nonlinear photonics and lasers.