Final answer:
Mansa Musa was the ruler who developed Timbuktu into a prestigious center of Islamic learning during his rule, establishing schools and the renowned Sankore University.
Step-by-step explanation:
The ruler who transformed Timbuktu into a center of Islamic learning and culture was Mansa Musa. During his reign from 1312-1337, Mansa Musa expanded the Empire of Mali to include Timbuktu and transformed it into a hub of international trade and Islamic education. He invited Arab scholars, as well as a range of other professionals, to enrich the city's knowledge base, leading to the establishment of over one hundred schools and eighteen universities dedicated to Islamic studies. Mansa Musa started the practice of sending students to Morocco for studies, which laid the foundation for Timbuktu's rise as a commercial and educational center in the Western Sudan.
The empire of Mali was created by Sundiata Keita, but it was under Mansa Musa's rule that Timbuktu flourished as a center of Islamic learning. Mohammed Askia I later continued Mansa Musa's work, culminating with the establishment of the Sankore University in Timbuktu.