Final answer:
Indigenous communities of the Pre-Columbian Great Basin and western Great Plains primarily engaged in nomadic lifestyles with economic activities focused on hunting, gathering, and fishing, rather than intensive agriculture or large-scale trade.
Step-by-step explanation:
The primary economic activities of indigenous communities in the Pre-Columbian era in the Great Basin and the western Great Plains were characterized by nomadic lifestyles centered around hunting, gathering, and fishing. These regions did not have the same level of intensive agriculture found in places like the American Southwest or the Eastern Woodlands. Communities such as those in the Great Basin and the western Great Plains had to adapt to their environment, and as such, their subsistence strategies were closely tied to the resources readily available in their areas, which prompted a nomadic or semi-nomadic existence.