These two verses describe three of David’s military policies:
He inflicted heavy losses on the enemy (about 18,000 casualties).
He forced them into vassalage (they became subject to David’s rule).
He placed army garrisons in the conquered land to keep control.
Edomites: In the ancient Hebrew script, the word Edomites looks very similar to Arameans. However, Edomites is more likely here. The Valley of Salt lies near the Dead Sea, which borders Edomite territory, not Aramean territory.