Ancient genomes from Southeast Asia (McColl et al. 2018 preprint)

Over at bioRxiv at this LINK. I'm still reading and trying to figure out what the 25 ancient genomes from this preprint say about the peopling of Eurasia and, in particular, South Asian population structure, including the so called Ancestral South Indian (ASI) genetic component. Any ideas? Below are the abstract and Figure 4 from the preprint.

Two distinct population models have been put forward