Complex sentence: During the rule of Sundiata Keita, these kingdoms were consolidated, and the Mandinka expanded west from the Niger River basin under Sundiata's general Tiramakhan Traore as part of creating a region of conquest, according to the oral tradition of the Mandinka people.
Split into simpler sentences: During the rule of Sundiata Keita, these kingdoms were consolidated, and the Mandinka expanded west from the Niger River basin under Sundiata's general Tiramakhan Traore. This expansion was a part of creating a region of conquest, according to the oral tradition of the Mandinka people.