Quite a long read, I must say. So basically, the author paints his comprehensive picture about Steppe as IE expansion, with lots of suppositions, on the back of all the ancient genetic research that we already know. Anti-steppiests will be furious. ;) Is the author Spanish? I hope he is not lynched by our in house anti-steppiest Iberians. ;)
Lot's of work went into these maps for sure. I'll have a closer look later.