There are six periods of human settlement with distinctive behaviours in UAE before Islam, which include the Hafit period from 3,200 to 2,600 BCE, the Umm Al Nar culture spanned from 2,600 to 2,000 BCE, the Wadi Suq people dominated from 2,000 to 1,300 BCE. From 1,200 BCE to the advent of Islam in Eastern Arabia, through three distinctive Iron Ages and the Mleiha period, the area was variously occupied by the Achaemenids and other forces, and saw the construction of fortified settlements and extensive husbandry thanks to the development of the falaj irrigation system.