Ghana's economic development and eventual wealth was linked to the growth of regular and intensified trans-Saharan trade in gold, salt, and ivory, which allowed for the development of larger urban centers and encouraged territorial expansion to gain control over different trade routes.Ancient Ghana ruled from around 300 to 1100 CE. The empire first formed when a number of tribes of the Soninke peoples were united under their first king, Dinga Cisse. The government of the empire was a feudal government with local kings who paid tribute to the high king, but ruled their lands as they saw fit.Established by King Sundiata Keita, known as the “Lion King,” the Mali Empire brought wealth, culture, and Islamic faith to West Africa.The wealth of ancient Mali was based on trade, particularly the trans-Sahara trade. Control and taxation of trade pumped wealth into the imperial treasury and sustained the Mali Empire's existence. The most profitable commodities traded were gold and salt.The Songhai Empire also transliterated as Songhay was a state that dominated the western Sahel/Sudan in the 15th and 16th century. At its peak, it was one of the largest states in African history.Songhai's economy was comparable to that of Mali and Ghana. They were based on commercial and commercial taxes. The Songhai Empire traded in many goods, including gold, kola nuts, and slaves for cowries, clothing, and salt. Songhai's architecture was also very creative and innovative.
Black holes themselves can not be seen, nor do they leave trails (since emptiness does not have to be caused by a black hole), but there is evidence for black holes: scientists can see the effects of their gravity on nearby stars. The answer is B.
