10th century CE, with Eze Nri denoting its leader. It was a political entity composed of villages, where each village was autonomous, independent with its own territory and name, and recognised by its neighbours. Villages were democratic, with all males and sometimes females a part of the decision-making process. Graves at Igbo-Ukwu (800 CE) contained brass artefacts of local manufacture and glass beads from Egypt or India, indicative of extraregional trade. The Aro Confederacy was a political union orchestrated by the Igbo subgroup, the Aro people, centered in the Arochukwu Kingdom in present-day south-eastern Nigeria. It was founded at the end of the 16th century, and by the 18th and 19th centuries their influence and presence reached across eastern Nigeria into parts of the Niger Delta and southern Igala. Later migrations Through pathways taken by caravan, or via travel amid the Almovarid period, a West African population (e.g., Sub-Saharan West Africans) may have introduced the –29 (A → G) β-thalassemia mutationfound in notable amounts among African-Americansinto the North African region of Morocco. Painted rock art from Manding peoples are found largely in Mali, where Malinke and Bambara peoples reside. The Manding rock art, developed using black, white, or red paint, is primarily composed of geometric artforms, as well as animal (e.g., saurian) and human artforms. Some of the Manding rock art may relate to circumcision rituals for initiates. During the 15th century CE, migrations from the northern area of Guinea and southern area of Mali may have resulted in the creation of Manding rock art in the northern area of Mali (e.g., Yobri, Nabruk), southeastern area of Burkina Faso (e.g., Takoutala, Sourkoundingueye), and Dogon country. Slave trade Following the collapse of the Songhai Empire in the 16th century CE, a number of smaller states arose across West Africa, including the Bambara Empire of Ségou, the lesser Bambara kingdom of Kaarta, the Fula/Malinké kingdom of Khasso (in present-day Mali's Kayes Region), and the Kénédougou Empire of Sikasso. European traders first became a force in the region in the 15th century, with the 1445 establishment of a Portuguese trading post at Arguin Island, off the coast of present-day Senegal. By 1475, Portuguese traders had reached as far as the Bight of Benin. The Atlantic slave trade began almost immediately after this, based on the already well-established slave trading capacity of the Islamic world, with the Portuguese taking hundreds of captives back to