After the conquest of the region by Alexander the Great and the subsequent wars between his generals, and according to the new interpretation of a new historical and iconographic source for Hellenistic history, a mosaic of Apamea discovered in 2011, proposed by Olszewski and Saad, the foundation of Pella, the Macedonian military camp ("") took place in the fall 320 BC, just after the Treaty of Triparadeisos (320 BC) at the initiative of Antipater, and Cassander's inspiration. In view of this interpretation, the authors disagree with the earlier hypothesises attributing the foundation of Pella to Alexander the Great or to Antigonos I Monophtalmos. From about 300 BC Pella receive a new status of "polis", was fortified and established as a city ("polis") by Seleucus who named it after his Bactrian wife, Apama daughter of the Sogdian warlord Spitamenes. The site was enclosed in a loop of the Orontes which, with the lake and marshes, gave it a peninsular form whence its other name of Cherronêsos. It was located at a strategic crossroads for Eastern commerce and became one of the four cities of the Syrian tetrapolis. Seleucus also made it a military base with 500 elephants, and an equestrian stud with 30,000 mares and 300 stallions.