To identify his (Zoroaster's) country, one has to take into account the importance they attach to cattle.
Notes from Wikiquote
La religion de l'Iran ancien by Duchesne-Guillemin, Jacques quoted in G. Gnoli. Zoroaster’s Time and Homeland: A Study on the Origins of Mazdeism and Related Problems by Gherardo Gnoli, Instituto Universitario Orientale, Seminario di Studi Asiatici, (Series Minor VII), Naples, 1980.