From east to west, Dhar Néma, Dhar Walata, Dhar Tichitt, and Dhar Tagant form a semicircular shape around the Hodh/Aoukar Depression, which, prior to 4000 BCE, was an area with lakes of considerable size, and, after 1000 BCE, was an area that had become increasingly dried.[4] During the emergence of the Tichitt Tradition, it was an oasis area.[4] The Tichitt Tradition of eastern Mauritania dates from 2200 BCE[5][6] to 200 BCE.[7][8]