Harvey Weiss studies the Mesopotamian record, in Iran, Iraq, Syria and Turkey, using archaeological and palaeoclimate records that provide high-resolution data for agricultural regimes, regional settlement patterns, and abrupt high-magnitude climate changes. He founded the Yale University Tell Leilan Project in northeastern Syria in 1978, and has directed extensive excavations at that ancient site along with several seasons of Leilan Region Survey surface reconnaissance. This archaeological research, along with paleoclimate researches, has generated new data and perspectives for understanding Mesopotamian societies’ dynamic agro-production, settlement distributions, and politico-economic histories as cities, states and empires evolved and collapsed during the past ten thousand years.