Looks like the answer%20and%20North%20Africa) has to do with the predominant religion in the area (if any)

Most of Europe and China consider Monday the first day of the (work) week, while North America, Israel, South Asia, and many Catholic and Protestant countries, consider Sunday the first day of the week, while Saturday is judged as the first day of the week in much of the Middle East (Israel excepted) and North Africa due to the Islamic influence.