The laboring classes, which in and of itself was divided, was constituted from farmers and skilled craftsmen to the outer rural population of the city. The inner situated craftspeople of various specialties were housed in complexes of apartments, distributed throughout. These encampments, known as neighborhood centers, show evidence of providing the internal economic backbone for Teotihuacan. Established by the elite to showcase the sumptuary goods that the resident craftsmen provided, the diversity in goods was aided by the heavy concentration of immigrated individuals from different regions of Mesoamerica. Along with archaeological evidence pointing to one of the primary traded items being textiles, craftspeople capitalized on their mastery of painting, building, the performance of music and military training. These neighborhood communities closely resembled individual compounds, often surrounded by physical barriers separating them from the others. In this way, Teotihuacan developed an internal economic competition that fueled productivity and helped create a social structure of its own that differed from the internal, central structure. Aforementioned craftspeople specialized in performing typical actions which in turn left physical evidence in the form of bone abrasions. Based on the wear of teeth archaeologists were able to determine that some bodies worked with fibers with their frontal teeth, insinuating that they were involved with making nets, like those depicted in mural art. Women's skeletons provided evidence that they might have sewn or painted for long periods of time, indicative of the headdresses that were created as well as pottery which was fired and painted. Wear on specific joints indicate the carrying of heavy objects over an extended period of their lives. Evidence of these heavy materials is found in the copious amounts of imported pottery, and raw materials found on site, such as rhyolitic glass shards, marble and slate. The residences of the rural population of the city were in enclaves between the middle-class residences or the periphery of the city while smaller encampments filled with earthenware from other regions, also suggest that merchants were situated in their own encampments as well.