I'm reading a new paper at PLoS ONE on the mitochondrial DNA of Iranians. It's the first study to tackle the topic of Iranian maternal ancestry using complete mtDNA sequences. Here are a couple of quotes that caught my eye:
Between the third and second millennia BCE the Iranian Plateau became exposed to incursions of pastoral nomads from the Central Asian steppes, who brought the Indo-Iranian language of the Indo-European family, which eventually replaced Dravidian languages, perhaps by an elite-dominance model [13,17,20].Derenko M, Malyarchuk B, Bahmanimehr A, Denisova G, Perkova M, et al. (2013) Complete Mitochondrial DNA Diversity in Iranians. PLoS ONE 8(11): e80673. doi:10.1371/journal.pone.0080673
The U5a1a’g cluster itself (based on HVS1 sequence data) is concentrated in populations of the Pontic-Caspian steppe, extending from Romania, Ukraine, southern Russia and northwestern Kazakhstan to the Ural Mountains. The highest frequencies of the U5a1a’g were reported in the Volga-Ural region (5.3%), in particular in Bashkirs (4.3%) and Tatars (3.9%) , although the frequency varies from ,2.7% in Russians to ,1.5% in populations of the northern Caucasus [64,76–81]. It is worth mentioning that despite the low frequency of U5a1a’g haplotypes in Central Asian populations of Turkmens, Karakalpaks, Kazakhs and Uzbeks (,1.5% according to the data of , some haplotypes were common between Karakalpaks (haplotype marked by mutation at np 16293), Turkmens (by mutation at np 64) and Iranians. So, it seems likely that the sub-cluster U5a1g or its founder has arrived to Iran from Eastern Europe/southern Ural via the Caspian Sea coastal route.