The Territorial Army is a Banner Army trainable by the Chinese consisting of changdao swordsmen and arquebusiers. The Arquebusiers are a good Ranged infantry unit good against Heavy Infantry and Light Cavalary, but vulnerable to Heavy Cavalry.
Changdao are good against Heavy Cavalry, and are overall strong in melee combat. Since the units compliment each other reasonably well, this army is commonly trained. It is even more powerful when mixed in with the forbidden army to offer Cavalry to your army to fend off enemy Ranged Infantry.