Say about this, is 30,000 is average size population for a Karak or this is larger than expected?
Even if the whole population is back it'd be the smallest of the Old Holds.
Forgive me for putting words in the mouth of the GM here, but, would it hit Ungor and stop? Unless each hold had their own line to Karaz-a-Karak, but rather went along the underways, then it would hit Ungor and stop because Ungor isn't reclaimed, and god would it be hell to even try that. Drunken Dynasty almost fuckin broke trying.
The Dwarves prefer redundancy, Karak Azul has its own line instead of going through K8P. Karag Dum is chained in via Vlag because it's such a huge distance from KaK.