Sentence:  Despite these and other strengths, however, the Iroquois became weakened throughout the seventeenth and into the early eighteenth centuries as they faced several ordeals: “first came massive depopulation from <WSD>imperial diseases</WSD>; next, a slide into economic dependence on trade with Europeans; then ensnarement in the imperial struggles of powerful French and English colonial neighbors; finally, direct incursions on Iroquois territory and sovereignty” (p. 2). 
Meaning of the word marked with <WSD> tags:  A communicable disease that is spread to indigenous people by conquering imperial forces.