i can simply add them in start pos

however, I ask another question. How do hordes gain points to the level of the empire? the number of armies and the number of hordes depends on the size of the empire. For the nations that build cities, it is clear to me. But I don't understand it in hordes.

good question. I think we need to reach other goals like technology and economics and therefore our empire grows. Maybe the number of tributary states u make is factor too.
i played a lot of times Hun hordes and other hordes who can settle, but still cannot tell u in detail.
If u like playing hordes and have the desert dlc i recommend Tanukhids, they have a very nice campaign with special missions to found a new empire smelting together different factions and cultures on ashes of ERE region.