People on the Move
At the top of the billing are movable factions - Hordes. These fall into two broad categories: Migrators and Nomads.
Nomadic Hordes
Attila’s Huns are a notable example of this playstyle, exclusively nomadic and unable to capture or build settlements. Instead, their vast cavalry armies act as ever-moving Encampments where rudimentary buildings can be constructed, and more units trained.
Rather than managing a settled economy, they rely on raiding the lands around them and razing the settlements of other factions to sustain and expand their armies. Those playing as a nomadic horde can also expect to be offered hefty sums of gold to spare potential targets from your onslaught. Whether you accept what is offered or take it all by force is up to you…
Lacking ties to any specific geographical area, they are free to carve a path of destruction in any direction and ravage any civilisation they come upon — in one campaign, they may sack Cairo and the entire Nile Delta, in another, they may reduce the hallowed city of Rome to ashes.
Migratory Hordes
A hybrid of the settled and nomadic, factions such as the Germanic Visigoths and Ostrogoths are known as Migrators. They begin the campaign much as any traditional Total War faction would, holding territory and developing settlements.
However, they face a multitude of existential threats (more on those later), and when the going gets tough, the Goths get going. By migrating, they may up-sticks entirely, scorch the earth behind them to deter pursuers, and temporarily become a mobile faction.
This allows them to relocate their entire population to new areas of the map, much as the Ostrogoths did after Theodoric the Great’s invasion of Italy and the creation of the Ostrogothic Kingdom centred on Ravenna.
Their unique resource is Population Growth. This is spent to construct buildings and to create new armies to move around the world map. Importantly, they are not able to grow while migrating. Instead, they must settle, even if temporarily, in order to accumulate resources, before moving on again.
While each migratory faction will have secondary objectives that guide players toward their historical destinations, you are free to move and settle wherever you please — but then, why move in the first place?