I have to respectfully disagree with this assessment. Columbia offers quite a few historians for South Asia including Profs. Dirks, Bakhle, and Rao. This fall the department will be hiring an historian who focuses on Islam in pre-modern and modern South Asia. Outside of the history department there's of course the plethora of professors in Anthro, Art History, and MESAAS (Middle East, South Asian, and African Studies). I'm not sure if it's gotten weaker, as they haven't lost any faculty or anything like that. Also, I don't think it's chaotic either: students study South Asia from a multitude of departments, but all the graduate students get to know each other/research/present papers through the South Asia Institute. I'm not trying to be a hack and say that Columbia is for every single potential South Asia history graduate student ever, but it certainly has its merits!