Wendorf, Schild, Applegate, and Gautier (Dynamics of Populations, Movements and Responses to Climactic Changes in Africa, Rome 1997) give a number of references to megaliths and menhirs along the north coast of the Mediterranean (Renfew 1981), a conceivable link to Stonehenge and other European megaliths, and megalithic alignments and stone circles in "Sahalian and sub-Saharan Africa from Ethiopia to Senegal and north to the Maghreb..." that are "especially numerous in West Africa where there are literally thousands of tumuli and megaliths" (Martin and Becker 1974, 1984, en francais). Wendorf et al. also mention "two older radiocarbon dates of 7440 BP and 6700 BP associated with megaliths in the Central African Republic," both of which are "rejected as too old." They are comparable in antiquity to Nabta. There is much more to be done!