Most communities south of the Senegal River Valley, however, were not thoroughly Islamized. The Serer people stood out as one of this group, who spent over one thousand years resisting Islamization (see Serer history). Although many Serers are Christians or Muslim, their conversion to Islam in particular is very recent, who converted on their own free will rather than by force, although force had been tried centuries earlier unsuccessfully (see the Battle of Fandane-Thiouthioune).