I have had stuff like that happen twice.

One time (Romans), when the Arverni lost their last settlement in Gaul. They started the trek to Galatia. And one time when I (Hayasdan) had torn the Seleukids apart. They still had Prophtasia and Sardis. And after they lost Sardis all Seleukid units in the west started a long, long, long, trek to Prophtasia.

On the first occasion I did not have war with the Arverni, so I had no issues with this great trek. On the second occassion, it was quite a humiliating experience for the Arche, having to go by Antiocheia, Edessa, Seleukeia Ekbatana, Susa, and Gabai (too bad they did not come past Persepolis), so I preferred them to be humiliated. Once they got back, I think I took Prophtasia within the year. :D