When did the world come to an understanding about uniform 7 days a week

 I have always wondered as to when did the world come to an understanding about uniform 7 days in a week, not withstanding the adjust ment factor of leap year and Adhika Maasa.

While I lived in Mysore, I wanted to raise this issue with Prof. Adyanadaka Krishna Bhat but could not do so. Now perhaps the venerable Professor may throw light on this aspect in greater detail.