The Abrahamic week did end on Saturday, which they probably got originally from the Vedic calendar as that is older and also has the last day of the week on a S

The Abrahamic week did end on Saturday, which they probably got originally from the Vedic calendar as that is older and also has the last day of the week on a Saturday, but Constantine moved the sabbath to coincide with his existing sun worship, so since then the situation has been confused and so calendars vary on which day to end with. In the UK you can generally find both examples on sale if you shop around.