The basic unit of Incan society is the alluyu. An Alluyu is a group of related families responsible for their assigned land and herds. Each alluyu was divided into equal halves. Each half would be composed of people from one lineage. Men and women from the two different groups would marry each other. This would keep land and labor in the same alluyu. Labor was exchanged for labor and this self-supporting unit accomplished many varied tasks. .
The close kin relationship between the different villages produced a different type of economy. Rather then looking outside the polity for specialized production each village was able to provide these items for the other. There would be no lack of access to any resource. For example, a family from a high elevation may be centered in a potato-growing zone. This family may send grandma off to tend the coca fields, which are a dayâ€™s walk from the main homestead. They may send a brother to herd llama in the highlands. This is looked at as a shared, community/family strategy. The result is that a single kin group has multiple settlements scattered around at various elevations. Murra coined the term â€œarchipelagoâ€ or Island group of little villages. .
In 1967 John Murra formally proposed an economical theory for Andean settlements. He based his theory on ethnohistorical documents that inspired a lot of archaeological research. This model describes a specific pattern of settlement location across the ecologically varied landscapes. Vertical archipelago explains the economical and social relationship found between these settlements. It was originally claimed to be uniquely Andean but it is now identified in the Himalayas and in the high volcanic Polynesian Islands.
Archaeologists use evidence of domestic habitation and material evidence of maintained identity links to a highland center to define or prove verticality. These are social and cultural ties to a core society.