This haplotype is thought to have originated in the Sahara during the Holocene Wet Phase around 7,300 years ago. Sickle cell variants descended from this ancestral haplotype comprise five haplotypes named after toponyms or ethnolinguistic groups (the Arabian/Indian, Benin, Cameroon, Central African Republic/Bantu, and Senegal variants), and another designation earmarked for atypical sickle-cell haplotypes.[22][23] Their clinical importance is because some are associated with higher HbF levels (e.g., Senegal and Saudi-Asian variants tend to have milder disease).[24]