Comahue
The region's social and economical centre is located at the point where the Limay and Neuquén rivers join into the Río Negro . 
<triplet> Limay <subj> Río Negro <obj> mouth of the watercourse <triplet> Neuquén <subj> Río Negro <obj> mouth of the watercourse <triplet> Río Negro <subj> Limay <obj> tributary <subj> Neuquén <obj> tributary