The next unit the Targaryens get is a unit of Dothraki Outriders. While the Screamers were the melee-centric unit for the starter set, the Outriders are its ranged troops. They have taken the art of horsemanship to an entirely new level. Like all cavalry, they get a free Maneuver action when they activate.
However, their Nimble rule makes them even quicker. It allows the Outriders to Shift 3” before making a Ranged Attack (as opposed to the usual 2”), and they can also make another 3” Shift after they attack. So, even though their Shortbows only have Short Range, they can still attack an enemy up to 15” away from where they started their turn, then move hopefully back out of retaliation range afterward.
An interesting thing about this unit is that they have absolutely no Melee attack at all. So, having that ability to shift away is certainly going to come in handy, as Targaryen commanders will need to make sure to not get this unit stuck in Melee.