In my world, there is an entire nomad-based society. While they have some influence based on gypsies, they are mainly based on Mongolian Horsemen. At some point in my fictional history (ca. 12th-13th centuries in our time), they eventually form their own major kingdom. However, despite creating formal cities an towns, they still continue to have their nomadic ways, not always staying in one place. Even though they are like this, how could a civilization that is nomad-based continue staying stable and structured?
For the notes:
While they move around a lot, they also use this to guard their territories and lands, and keeping their military mobile
Some "villages" are just nomadic groups that move around, creating temporary structures and mainly living in wagons/carriages like gypsies
Their main food is livestock, and being a rancher is a huge industry there
Some of their "cities" are giant groups of travelers
Geographically, the kingdom is in a huge, wide valley
Some permanent structures include tradeposts and military fortresses near the borders