When Mushki and Urumu appeared in Early Iron Age, they had an ally. A Kashkian tribe Apishlu. Ever wondered where his name is probably preserved? Well in Colchis region. Apshel-k' in Armenian or Apshil-eti in Georgian. And they seems to be a branch of Abkhazian, which is normal because Kashkians are sometimes linked with NWC people.
Yet another piece of evidence that Mushki and Urumu came from North Eastern regions of modern Turkey. From the backyard of Hayassa-Azzi.
PS Well it is possible that Urumu's initial homeland was not to North but it is not crucial.