Part of the problem is determining what we mean by writing. Keep in mind we don't see any long inscriptions of the sort we see in early Sanscrit or Hittite. O

Part of the problem is determining what we mean by writing. Keep in mind we don't see any long inscriptions of the sort we see in early Sanscrit or Hittite. Only a few areas are attested including stamp seals, pottery and the like. The Indus Valley script could have been, for example, a pictographic/ideographic labelling system without any real language-encoding function. But if I draw thee fish to indicate that you owe me three fish, is that writing? It's certainly encoded communications. I don't know that it is writing as we know it though.