You have a pretty simple idea of south asian admixture in Afghanistan.
I never said it ALL came recently to Afghanistan. Of course it's old, though it would had been brought by Indus pastoralists.
AASI has no proof of existing even in Hindukush 4000-8000 BCE or north of it. Example a Mesolithic sample from Tutkaul, Tajikistan lacks AASI. We can from there already see on lowland Bactria AASI was non-existent that long ago. There's no proof of it existing in Hindukush, without west eurasian pastoralists brining the admixture.
Of course perhaps 3000-2000 BCE you'll start seeing AASI admixture in hindukush mountains. West eurasian pastoralists brought that, even as far north into Turkmenistan and Uzbekistan.
You're right about the indo-iranian intrusion to south of amu river, so I'm not gonna dwell much into that.
But claiming pashtuns never mixing with indics is very ignorant. Already by their haplogroups alone, we can see them pick up indic R1a's, L's, even AASI H clades and R2's too, the specific subclades that example doesn't exist much in hindukush populations that didnt historically mix with pashtuns (much). Those specific clades are also much closer to indic populations such as punjabi subgroups and brahuis (who are native to Suleiman mountains).
Of course pashtuns always had IVC admixture, even farmers all north in Bronze Age Uzbekistan were like 7-15% IVC before mixing with aryans. Pashtuns would seemingly been in north or central Afghanistan originally based on historical accounts, issues of linguistics. Seemingly around possibly this black circled part:
Attachment 144854
Obviously they genetically would been akin to the people in that particular area, though without turkic ancestry. But the north hazarajat locals, especially northwestern ones, aren't exact the same as hindukush populations, such as kalash or nuristanis. Those locals probably plot between dards and north shifted populations such as yaghnobis and khorosan persians. Pashtuns would originally been akin to that.
At that time, pashtuns certainly wouldn't had any of these Suleiman mountain haplogroups they regularly pick today. Moving southeast for some reason towards Kabul, Nangarhar and then Suleiman mountains in 400-500 CE, they settled there. The inhabitants of the mountains were refered as indians, by both greeks, indirectly by chinese and directly by muslim writers from 300 BCE to 1000 CE. They would most likely had been just alike the punjabi inhabitants right east of the mountains, whom shares clades with pashtuns.
Given that fact, pashtuns would had mixed with the locals and increased their south asian admixture. How much exactly? I don't know, but I do know they mixed with indians. It's not a theory, haplogroups clearly shows this.
So you're completely wrong about pashtuns not having mixed with indics. They have. But pashtuns, alike balochs, are a special case. They're a group that immigrated from one place, not much near indians or near at all, to another, mixing with the indian locals. In case of pashtuns, from somewhere in north Afghanistan to Suleiman mountains. In case of balochs, from Mazandaran, through Kerman, to pakistani Makran (indian locals too, such as zutts and brahuis)
So what I'm saying:
-Pashtuns already had chunks of IVC prior mixing with indics
-Pashtuns increased IVC further, probably 30-50% in 500-1000 CE