Bumping this. It's an obscure, but interesting PoD.
Ahmad Sanjar's earlier death would mean a different partition of the Seljuq Empire, which has long-term repercussions. Of course, it could also butterfly away Chengis Khaan (born around 20 years after the PoD), which means that an emboldened Kara Khitan, having defeated Central Asia's pre-eminent power and killed its ruler, could survive longer...
The consequences of Garshasp II escaping with his life are less obvious, I partly posted this thread to hear the opinion of the fine folks of AH.com
