The main reason San Lorenzo flourished at such an early period is its location within the Coatzacoalcos flood plain, which provided fertile land for farming. Thus, the settlement of San Lorenzo follows the pattern of settlement of the world’s very first urban centers, which emerged in the fertile river valleys of Mesopotamia. Because of the high farming value of the surrounding land, San Lorenzo ranked as the Olmecs’ most populous settlement from 1200-900 BC. During that period, San Lorenzo had the biggest trade market in all of the Olmec Heartland.