They are also called meridians.
Because of Mansa Musa's pilgrimage across the world (where he showcased his wealth) the kingdom of Mali gained enormous economic success and recognition. When he went on tour showcasing his wealth to everyone he saw, he arguably became the worlds first 'celerity'. Because of his immense wealth and popularity, word got around quickly on how powerful and wealthy the kingdom of Mali is, and many scholars and all sorts of people flocked to Mali. Mansa Musa built mosques and learning centers, and Mali became a hub of learning and a bustling city. Because Mansa Musa gained celerity like status, others recognized Mali as a good place to make money, learn, worship, and live. Because of this boost of population, Mali's economy grew immensely.
Hope this helps! (you might want to look up certain dates and specifics of his pilgrimage, I hope this is a good outline though!)
