Mesh topology is popular for Network on Chip (NoC) architectures because it has many desirable fabrication and performance properties, due to fixed sized rectangular tiles for resources. Region concept has been proposed to handle cores with larger size than the tiles. In this paper, we present an elaboration of the region concept, pointing out new design issues and possibilities. Special routing algorithms are required for deadlock free communication to handle blockage introduced by the regions. We show that fault tolerant algorithms developed for multi-computer systems can be adapted for this purpose. By simulation, we study the introduction of rectangular regions in a 7X7 NoC. Our study shows that the position and orientation of regions have a strong influence on achieved network performance.