 One model (Tammetal 2007) based on Native American mtDNA Haplotypes (Figure 2) proposes that migration into Beringia occurred between 30k and 25k cal years BP, with migration into the Americas occurring around 10k to 15k years after isolation of the small founding population.Another model (Kitchen et al.2008) proposes that migration into Beringia occurred approximately 36k cal years BP, followed by 20k years of isolation in Beringia.