I think Herodotus wrote about Scythians but I don't remember him offering any explanations on their origins. He says they didn't use stirrups or saddles and their women were excellent fighters too, which gave rise to the myth of Amazons. From what it seems the women were equal with men in all aspects of society.
Sythians were also big fans of cannabis They used it for clothing, and getting cleaned in its smoke and getting stoned of course
I remember reading somewhere how Alexanders army when first encountered the Scythians got really stoned and didn't wanna leave
They were the first to domesticate horses and the first to use them in warfare. They used poisonous arrows and darts from horseback. They drank the horses blood.
Scythians were not turks in any way. They got extinct around 100BC but the Eastern Romans kept referring to the Eurasian mounted barbarians as Scythians, which became a word to describe a eurasian mounted barbarian. Turks are mongolian tribes which came to Europe long after the Scythians were extinct. The true origins of Scythians are unknown from what I know.
Greco Scythians were Scythians that came to Greece. Like the Scythian philosopher Anacharses who came to athens in the 6th century B.C and became very wise and popular.
On another note Indo-European theory is a joke. THere is no such thing as a Indo-European tribe or language. It is just a myth the scientists have devised to explain similarities in language, customs and DNA of European peoples. There is no real scientific evidence to support it. No evidence of a "tribe". No explanation of where they came from and most importantly why did they move or seperate into different tribes. Also if there was really a people which then became different people, how can one explain the huge differences in language, culture and civilization? Why did some of them become really advanced and civilized and some of them devolved into barbarians?
The similarities are there of course and nobody can deny them. But they can be more easily explained with the presence of an ancient, advanced culture which influenced all of these different people, others to a bigger extent others to a smaller.
Sorry for this but I hate it when people take the Indo-European theory as granted when it is nothing more than a hypothesis, and a weak one as such.