time during the following Ur III period, rivalries between pastoralists and farmers increased. Attempts were undertaken to prevent the former from herding their flocks in agricultural lands, such as the building of a wall known as the "Repeller of the Amorites" between the Tigris and Euphrates under the Ur III ruler Shu-Sin. Such attempts led to increased political instability; meanwhile, severe depression occurred to re-establish demographic equilibrium with the less favorable climatic conditions. Richard Zettler has critiqued the drought theory, observing that the chronology of the Akkadian empire is very uncertain and that available evidence is not sufficient to show its economic dependence on the northern areas excavated by Weiss and others. He also criticizes Weiss for taking Akkadian writings literally to describe certain catastrophic events. According to Joan Oates, at Tell Brak, the soil "signal" associated with the drought lies below the level of Naram-Sin's palace. However, evidence may suggest a tightening of Akkadian control following the Brak 'event', for example, the construction of the heavily fortified 'palace' itself and the apparent introduction of greater numbers of Akkadian as opposed to local officials, perhaps a reflection of unrest in the countryside of the type that often follows some natural catastrophe. Furthermore, Brak remained occupied and functional after the fall of the Akkadians. In 2019, a study by Hokkaido University on fossil corals in Oman provides an evidence that prolonged winter shamal seasons led to the salinization of the irrigated fields; hence, a dramatic decrease in crop production triggered a widespread famine and eventually the collapse of the ancient Akkadian Empire. Government The Akkadian government formed a "classical standard" with which all future Mesopotamian states compared themselves. Traditionally, the ensi was the highest functionary of the Sumerian city-states. In later traditions, one became an ensi by marrying the goddess Inanna, legitimising the rulership through divine consent. Initially, the monarchical lugal (lu = man, gal =Great) was subordinate to the priestly ensi, and was appointed at times of troubles, but by later dynastic times, it was the lugal who had emerged as the preeminent role, having his own "é" (= house) or "palace", independent from the temple establishment. By the time of Mesalim, whichever dynasty controlled the city of Kish was recognised as šar kiššati (= king of Kish), and was considered preeminent in Sumer, possibly because this was where the two rivers approached, and whoever controlled Kish ultimately controlled the