I'm sure bronze weapons in Maykop kurgans came from Kurdistan Zagros Mountains (Iranian Plateau)
Early fourth millennium bronze artifacts has been found in Zagros.
http://www.jstor.org/stable/530550
I think we still need to analyze more Maykop and steppe samples bronze and copper samples. I know that on the steppe copper is coming from the Balkans first, then there is clear stylistic influences from the Caucuses by the time Yamnaya, which also coincides with steppe people beginning to mine copper from their own sources in the Urals. I think Bronze from Zagros makes perfect sense, but the Aegean is very early as well