In addition to today's news that Patch 7 for Total War: Rome 2 is now out and available for download, Creative Assembly has announced that it plans to release a new faction—the Baktria—as a free DLC update.
Baktria is adjacent to Parthia, so players will face an early challenge against the formidable empire. No date has been given for when players will be able to take on the role of the Baktria, but one assumes that it shouldn't be too far from release given the announcement today.
The announcement was made as a part of Creative Assembly's on-going Rally Point series, of which the latest episode can be seen below.