Proto Indo European Homeland is a hostile land with little resources. Compare that to Anatolia, Transoxania,Balkans,Italic Peninsula,Iberia,Gaul,Tarim Basin and Kashmir(the territories covered in the first wave). Scythians were the ones who dominated the PIE homeland before eventually Russians and Ukrainians took over. Even they migrated into Europe(it's said that they are the ancestors of Hungarians,Balkan Slavs in part) and India(ancestors of Jatts,Khatris,Nairs,Tulu Bunts,etc,etc). So that's not a worthy land. If say all Indo Europeans migrated to one place as a huge confederation and start massive cities like the Ancient Mesopotamia,it could be possible.
Within no time,Tocharians split into the Afanasevo culture and Indo-Iranians (probably even Balto-Slavs) went into the Sintashta culture and eventually Indo-Iranians went into the Andronavo culture. The Anatolian Lydians,Phrygians,Hittites,etc went off quickly into the Anatolia. So that precludes this already. Say all Proto-Indo-Europrans cross the Caucasus mountains and the Black Sea into Anatolia,ME and Balkans like the Anatolians before all these splits happened,this could be possible. Anyway @metalinvader665 is quite an expert in these things.
Is it poor though? Ukraine is certainly not a poor homeland and civilization centre.