Video from 2014. Part Two here.
"The genetic variation within the Scythian nomad group is so broad that it must be explained with the group assimilating people it came in contact with. This is shown in a new study on Bronze and Iron Age genetics of the Pontic-Caspian Steppe, situated in the Black Sea region." Source: Science Daily.
"...The vast area of the Pontic-Caspian Steppe region has worked as a motor for demographic events throughout Eurasia, especially in the western part of the meta-continent. Crucial events in European history and prehistory can be traced back to people of the Steppe. Including the invention of horseback riding, chariots, a new type of warfare and the spread of Indo-European languages ."
 "The Kurgan hypothesis (also known as the Kurgan theory or Kurgan model) or steppe theory is the most widely accepted proposal to identify the Proto-Indo-European homeland from which the Indo-European languages spread out throughout Europe, Eurasia and parts of Asia. It postulates that the people of a Kurgan culture in the Pontic steppe north of the Black Sea were the most likely speakers of the Proto-Indo-European language (PIE). The term is derived from the Russian kurgan (курган), meaning tumulus or burial mound." (Wikipedia)