Final answer:
The southeast tribes' reasons for waging war were land disputes, tribal rivalries, defense against European encroachment, and economic competition, often intertwined with the concept of communal land rights versus European private ownership.
Step-by-step explanation:
The southeast tribes waged war for a variety of reasons, and these can often be interlinked. However, the primary motives for conflict included land disputes, tribal rivalries, defense against European encroachment, and economic competition. The concept of land as communal versus the European view of private ownership often led to significant conflict as settlers encroached on traditional hunting grounds, igniting disputes over land use.
Tribal rivalries, too, could result in warfare as demonstrated by the strategy known as counting coup, which was a testament to bravery, and served the purposes of prestige and vengeance within tribal cultures. Economic competition arose both amongst tribes and with Europeans, particularly as the latter sought to exploit natural resources for economic gain, a motive that also played a role in the tragic displacement of tribes onto reservations.