Hi artists of 0ad, the nomadic factions need some additional buildings to fill up the tech tree and round out their content:
Royal Yurt (xiongnu) : This is supposed to be a larger and more decorated yurt that would house the leaders of smaller subgroups within the xiongnu people as a whole. Each royal yurt will allow for 3 warlord units and provide 10 pop just like a house.
Dock (xiongnu/scythians): This should be a very simplistic building. Its completely ahistorical, but a necessary structure for the nomads to fit in. It could basically be a yurt on land with a rope ladder serving as a boat ramp. Possibly some scrap wood could be added, or the 'skeleton' of a small canoe or river boat.
Stable (xiongnu/scythians): This should be a simple cover for horses and/or equipment, possibly tarp-based. A small fence would complete the structure, making it rectangular.
Ovoo (Scythians): The scythian ovoo is currently the xiongnu one, where it was actually built differently with mostly wood piled up and an ornament at the top.
Wonder (Scythians): Kurgan (burial mound).
https://www.cam.ac.uk/stories/gold-of-the-great-steppe-exhibition
Some help on these items would be awesome!