The Sharon Plain suffers from drainage problems and poor soil. For much of history, the region was only sparsely inhabited, suffering severe demographic fluctuations. The Iron Age IIA stands out as a period during which settlement in the Sharon, and especially in the Yarkon basin (the Sharon’s southernmost part), reached a peak before plummeting in the Iron Age IIB. What caused this unusual fluctuation? The only reason to build new settlements in the swampy Sharon was for serving as an inland polity’s outlet to the sea, so the key is to understand who could benefit from investing in this region, and especially in the Yarkon basin. A center in Samaria or the Hebron hill country would have had better port cities – Dor or Ashkelon, respectively. Only a polity with a center in the area around Jerusalem could benefit – and greatly so – from a port in the Yarkon basin. This, along with other lines of evidence (e.g., Excursus 8.1), suggests that the highland polity expanded to this area and controlled it for a few generations. Once the United Monarchy collapsed, there was no incentive to maintain the swampy region and the settlements were gradually abandoned.