House Dawnsinger's Ren'dorei chapter was formed out of the remnants from the Dalaran Onslaught. These followers of Teran Dawnsinger were eventually inspired to join ranks with his eldest child, Serana Dawnsinger and her Order of Dawnshire.
After the Siege of Quel'Damor, the Ren'dorei chapter was largely absorbed into the Dawnish population.