The Halpulaar (Pulaar-speakers), composed of Fula people, a widespread group found along the Sahel from Chad to Senegal, and ''Toucouleurs'', represent 23.8 percent of the population. Historically, they were the first to become Muslim. Many of the ''Toucouleurs'', or sedentary Halpulaar of the Senegal River Valley in the north, converted to Islam around a millennium ago and later contributed to Islam's propagation throughout Senegal. Success was gained among the Wolofs, but repulsed by the Serers.