Before revision: Those set in relative upland , large-vessel navigable or arid drainage basins were (as with major confluences ) for trade and defence favorable to found forts, governing army camps or cities.
After revision: Knees navigable by large vessels or set in upland areas or arid drainage basins were similar to major confluences in that they were particularly suitable for trade and defense, and therefore gave rise to forts, governing army camps or cities.