proto-Indo-European geography.

I see there are quite a few Eastern Europeans on this list. I'd be interested in their personal observations of what their own local geography and the kind of geography they were taught in school teaches them about the IE migrations. Here in the US, we are taught very little about European geography, and in particular, Eastern European and Central Asian geography. I doubt very much that you'd find more than 1 in 100 college freshmen who've every heard of the Yenisey River.

My main questions concern what is possible in terms of migration routes. When moving from Eastern European into 'Middle Europe' (west of the Carpathians), my impression is there are only three real possibilities.

The first is via the Bug or Dneister to the Tisza -- i.e., into Hungary. By my understanding, the Transylvanian Alps are not what you would think of as a migration route; the Iron Gate of the Danube was an impassable cataract. A secondary route would have been at the far south, in modern Bulgaria/Thessaly. The third route, the most difficult of all, would be along the coast of the Baltic Sea. A transit of the Pripet marshes, while not impossible, was always difficult; you'd need a 'native guide'.

One on the plains of Hungary, the routes are then via the Danube west (and via the Seine, to the Atlantic) or south on the Danube to modern Belgrade, and then via the Morava (the southern one, the one that goes up near Skopje), and then down the Vardar to Aegean Sea.

The second big question is exactly what the word 'steppe' means, especially to a Russian. In English, it refers to a relatively flat treeless expanse covered with seasonal grasses. An analogous region is the US Great Plains, ranging from just west of the Mississippi clear to the foot of the Rocky Mountains: historically, "an ocean of grass", just as the Russian steppe has been described. At the same time, however, you encounter the term 'forest-steppe', which seems contradictory, even oxymoronic: exactly what does 'forest-steppe' mean to you? I imagine it to mean a transition zone between grasslands and the dense Northern (Boreal) Forest, but I could be wrong.

How difficult is the 'coastal route' along the Eastern shore of the Black Sea? Is it wide and flat, with lots of fresh water, or is it steep and rocky, difficult to move along, particularly if you have a herd of cattle with you, without being harassed by natives up in the hills?

There are other questions too. I have only the vaguest idea of how easily one enters the Russian river valleys as you cross from east to west. In the US Great Plains, you can encounter some pretty steep, cliff-lined valleys, but on the whole, it's a gentle rise from the level of the river to the highest ground -- undulating, low hills, easily traversed by livestock.

What I'm looking for are the logical late neolithic - eneolithic -early bronze age routes the PIE's would have taken.