The origins of the Hurro-Urartians and an update on the possible source of haplogroup R1a-M17/M198 for the Indo-Iranians

the Kassites are said to be a group of people who are similar to the Hurro-Urartians in terms of linguistics the study by Lazaridis, Alpaslan-Roodenberg et al. 2022 noted how Levant_PPN related ancestry heavily increased with some samples reaching around 33% this ancestry might might be a representative of the reason behind the existence of non Indo European languages like Elamite aswell.

the following information is from Supplementary Materials for The genetic history of the Southern Arc: A bridge between West Asia and Europe by Iosif Lazaridis, Songül Alpaslan-Roodenberg et al. 2022. 

Levant_PPN related ancestry was 9% on average during the existence of the Kura–Araxes culture while 1 samples had this ancestry at around 24% around that time.

during the MBA 3 samples also had this ancestry at around 25%.

during MBA to LBA it increased by a few more percentages with an outlier reaching around 19% with the averages reaching somewhere between 12-15%.

and during LBA to EIA there's an outlier with this ancestry at around 20%.

from the EIA to the Urartian period we see the appearance of an outlier with this ancestry at around 27%.

5 Urartian Samples from Turkey literally reaches around 33% with this ancestry as well. 

and now coming to another possible source of haplogroup R1a-M17/M198 for the Indo-Iranians it seems like Tepe_Hissar_C also has WSHG related ancestry at around 5% based on Narasimhan et al. (2019) File (aat7487_narasimhan_sm.pdf) and a similar percentage based on the study of the Spatial and temporal heterogeneity in human mobility patterns in Holocene Southwest Asia and the East Mediterranean by Koptekin et al., 2023 so this route also seems to be possible.