The Neolithic Subpluvial was an extended meteorological period, from about 7,500-7,000 BC to about 3,500-3,000 BC, of relatively wet and rainy conditions in the climate history of northern Africa. It was both preceded and followed by much drier periods. Several archaeological sites that date from this time, often identified as part of the Tenerian culture, are dotted across the deserts along the borders of Niger, Algeria and Libya. The human population dwindled as the Sahara dried out, and by 2500 BC, it had largely become as dry as it is today.