Answer :
Mansa Musa I of Mali was an emperor of the Malian Empire during the 13th-14th century. After research, it was discovered that if inflation was applied to the amount of the emperor's wealth, it would turn out that the emperor was the richest man to exist in the past 1,000 years, having a 2014 wealth value of $400 billion. Musa I was a devout Muslim, and he spent quite an effort spreading the Islamic religion across his empire. He is known for his ostentatious pilgrimages to Mecca, bringing a procession of 60,000 men, and 12,000 slaves that all carried gold bars to Mecca. Some (if not most) of the mosques that he has built are still standing today.