Long distance transport of goods by way of camelid caravans was well established in the prehispanic Andes. The strongest evidence for the importance of caravan transport comes in the form of ethnohistoric and ethnoarchaeological studies described earlier in this chapter, however archaeological evidence of caravan traffic is usually very light and it often requires inference from indirect evidence. The "Independent Caravans Model" described here consists of caravans organized on the household level, although ethnographic studies show that, in practice, the members of several households will often band together for company and for safety while participating in long distance caravans. It is worth pointing out that independent long distance transport does not necessarily involve cargo animals. It is possible that small quantities of obsidian were carried bytraveling peddlers. As a variant to this model, one should consider that peddlers carrying small portable items, mostly cultural goods like herbs, shell, feathers, but potentially small obsidian tools or cores, could have circulated objects widely without the assistance of llamas.
According to this model, a household with a sufficient number of cargo animals, usually castrated male llamas, will initiate a trade caravan by transporting goods that they expect will be in demand, to regions that they anticipate will have complementary goods to offer them. According to some descriptions, caravans are pursuing a directed acquisition of specific goods and then they return directly home, while other models describe entire circuits where herders acquire goods, travel, barter for other goods, travel some more, perhaps re-trade their new goods and so on; finally returning to their place of origin several months later.
The mere presence of products distributed over larger distances is not proof of caravan transport, either household organized or administered, because other modes such as direct acquisition and down-the-line models actually result in widely dispersed goods as well. Furthermore, many of the distinctive objects that archaeologists recognize as non-local are often small enough to have been transported without cargo animals. Establishing the beginnings of caravan transport is not a simple task because there is no one signature for long distance caravan organization that is distinctive from other modes of transport. Furthermore, many of the goods are believed to have been perishable, complicating efforts to interpret prehispanic trade caravan patterns. Finally, studies of contemporary caravans emphasize that diversified strategies characterize caravan driving, whether in making daily decisions while on the trail, or in the larger context of economy and exchange. It is thus difficult to define a consistent indicator for caravan activity.
Portable diagnostic artifacts, whether decorated ceramics or other exotic goods, are often relatively small and therefore the artifact weight and total quantity frequently cannot be used to differentiate between caravan transport, traveling peddlers, and down-the-line exchange. The temporal regularity of exchange, however, is a consistent measure that archaeologists can recover from stratified deposits. When regular caravan transport routes developed then the scheduling of such transport may have been linked to the timing of annual events such as harvests and annual ceremonies, and if so these cyclical patterns would result a steady accumulation of non-local goods through time. In contrast, down-the-line exchange depends upon the articulation of many individual exchanges and it is not linked to the acquisition of scheduled harvest products in the same manner as caravan transport and therefore the presence non-local goods would have been irregular.
In terms of the network configurations discussed earlier (Figure 2-3), the configuration that describes the diffusion of obsidian in the region is distinct from the configuration of the regular articulation between herders and farmers that involved the barter of pastoral products for agricultural products. However the regular conveyance of some agricultural goods adjacent to a raw material source creates a context for conveying larger quantities of obsidian regionally. Ethnographic studies indicate that caravans will opportunistically embed exchange into other activities. For example, Nielsen (2000: 488) explains that caravans primarily organized around salt transport would carry a variety of other trade items, and they would occasionally stop to procure raw materials, such as lithics, when the caravan route travels past a known source. Similarly, there is caravans that visited the Colca valley in prehistory from the Titicaca Basin were passing with 3 km of the Chivay source if they used one of the popular routes into the Colca from the south-east direction. Thus, procurement of obsidian was likely to have been associated with long distance exchange opportunities.