[fourtrees]

I feel like I ought to note that there's no evidence of military activity (that I know of) in the IVC, but certainly evidence of violence: https://libres.uncg.edu/ir/uncg/f/G_Robbins_Schug_Peaceful_2... . I wish it weren't the case, but it seems early Harappan scholars made the same error that early scholars of the Minoans did in concluding that the absence of evidence of violence implied the absence of violence itself. Of course, this doesn't mean that the IVC wasn't a relatively peaceful place compared with places like Sumer or Elam, like you said.

[ncmncm]

Military activity is not the only kind of violence.

I think evidence of military activity would involve obvious weapons and armor, which have generally been easy to recognize and easy to distinguish from e.g. hunting or ranching equipment. The paper linked notes a prevalence of head trauma, presumably with clubs. It doesn't suggest to me any pattern like religious sacrifice or criminal execution. So, the nature of the violence is hard to discern.