Sorry for the flippant remark, but I obviously don't have the intellectual drive to ponder such that actual historians do......glad there are such as you to keep a little bit of educational interest in so many fascinating things about civilization and development.
:') Having herds to drive would automatically made a nomad a trader, it seeems to me. Other goods would be things they'd picked up along the way but didn't need, presumably pretty compact things. And like any other durable population, their largest asset was their skill set.