In the entire eastern region, there are passes and there is narrow valley route that connected Yindu and the Great Steppe but there is not a route or road to field large armies
Not to mention because there is no feud and no reason.
Both Yindu and the Great Steppe did not have such animosity and instead most of their interaction between these two civilization is mostly trading
But that is not the same relationship that the Steppe people have with Yan, Zhou and Roma.
These three empires and the kingdoms and states that is between them and these empires all have deadly feud.
Yan had always massacre the people different from them.
Roma is arrogant and the same as Yan. The Zhou are the losers of the central plains and manage to establish tehri kingdom in a different region but they still have that arrogance even though that arrogance itself is more of a mask trying to gain some legitimacy for their dynasty
