Scholars have not reached a consensus on the number of migrants who entered Britain in this period. Härke argues that the figure is around 100,000 to 200,000. Bryan Ward-Perkins also argues for up to 200,000 incomers. Catherine Hills suggests the number is nearer to 20,000. A computer simulation showed that a migration of 250,000 people from continental Europe could have been accomplished in as little as 38 years. Recent genetic and isotope studies have suggested that the migration, which included both men and women, continued over several centuries, possibly allowing for significantly more new arrivals than has been previously thought. By around 500, communities of Anglo-Saxons were established in southern and eastern Britain.