Along with nearby terracotta jars used in ritual sacrifice, hooked arrowheads made of iron were also found. Beads made of quartzite, nose rings made from brass, and bracelets made from iron or brass were found on human remains located beneath the terracotta jars. Within the region of the Niger River basin, the Bura culture produced the earliest terracotta equestrian statuettes. It is not yet known how the Bura culture is connected with other ancient African cultures and with later Islamic-influenced Sahelian kingdoms such as Ghana, early Mali, later Mali, or Songhai. The terracotta urns of the Bura culture, which were used for funerary purposes, may be related to the Tondidarou megaliths. Sahelian kingdoms The Sahelian kingdoms were a series of kingdoms or empires that were centred on the Sahel, the area of grasslands south of the Sahara. The wealth of the states came from controlling the trade routes across the desert. Their power came from having large pack animals like camels and horses that were fast enough to keep a large empire under central control and were also useful in battle. All of these empires were also quite decentralised, with member cities having a great deal of autonomy. The Ghana Empire, Mali Empire, and Songhai Empire acquired gold utilizing alluvial methods of mining in Bambuk. Ghana The Ghana Empire may have been an established kingdom as early as the 3rd century CE, founded among the Soninke, a Mandé people who lived at the crossroads of this new trade, around the city of Kumbi Saleh. Ghana was first mentioned by Arab geographer Al-Farazi in the late 8th century. After 800, the empire expanded rapidly, coming to dominate the entire western Sudan; at its height, the empire could field an army of 200,000 soldiers. Ghana was inhabited by urban dwellers and rural farmers. The urban dwellers included the administrators of the empire, who were Muslim, and the Ghana (king), who practised traditional religion. Two towns existed, one where the Muslim administrators and Berber-Arabs lived, which was connected by a stone-paved road to the king's residence. The rural dwellers lived in villages, which joined into broader polities that pledged loyalty to the Ghana. The Ghana was viewed as divine, and his physical well-being reflected on the whole society. Ghana converted to Islam around 1050, after conquering Aoudaghost. The Ghana Empire grew wealthy by taxing the trans-Saharan trade that linked Tiaret and Sijilmasa to