the sedentary lifestyle used by farmers led to increased warfare, which was detrimental to farming and brought this period to an end. Qadan culture The Qadan culture (13,000–9,000 BC) was a Mesolithic industry that, archaeological evidence suggests, originated in Upper Egypt (present-day south Egypt) approximately 15,000 years ago. The Qadan subsistence mode is estimated to have persisted for approximately 4,000 years. It was characterized by hunting, as well as a unique approach to food gathering that incorporated the preparation and consumption of wild grasses and grains. Systematic efforts were made by the Qadan people to water, care for, and harvest local plant life, but grains were not planted in ordered rows. Around twenty archaeological sites in Upper Nubia give evidence for the existence of the Qadan culture's grain-grinding culture. Its makers also practiced wild grain harvesting along the Nile during the beginning of the Sahaba Daru Nile phase, when desiccation in the Sahara caused residents of the Libyan oases to retreat into the Nile valley. Among the Qadan culture sites is the Jebel Sahaba cemetery, which has been dated to the Mesolithic. Qadan peoples were the first to develop sickles and they also developed grinding stones independently to aid in the collecting and processing of these plant foods prior to consumption. However, there are no indications of the use of these tools after around 10,000 BC, when hunter-gatherers replaced them. Harifian culture The Harifians (8,800 – 8,000 BC) are viewed as migrating out of the Fayyum and the eastern deserts of Egypt (including Sinai) during the late Mesolithic to merge with the Pre-Pottery Neolithic B (PPNB) culture, whose tool assemblage resembles that of the Harifian. This assimilation led to the Circum-Arabian Nomadic Pastoral Complex, a group of cultures that invented nomadic pastoralism, and may have been the original culture which spread Proto-Semitic languages throughout Mesopotamia. Neolithic Lower Egypt Faiyum A culture Continued expansion of the desert forced the early ancestors of the Egyptians to settle around the Nile more permanently and adopt a more sedentary lifestyle during the Neolithic. The period from 9000 to 6000 BC has left very little in the way of archaeological evidence. Around 6000 BC, Neolithic settlements appear all over Egypt. Studies based on morphological, genetic, and archaeological data have attributed these settlements to migrants from the Fertile Crescent in the Near East returning during the Egyptian and North African Neolithic, bringing agriculture to the region.