How come there is 7 days in a week in all civilization?

The 7 day 'week' originated in the ancient Near East in Sumer and Babylonia among the 1st/ earliest civilizations so being 1st it had a big influence. It spread to all the Mideast, central Asia, North Africa, Europe. The Babylonians really spread it a lot because they were so big into astronomy/ astrology they knew well of the 28 day month (the time it takes the moon to revolve around the earth), and that 12 such cycles made '1 year' (the time it takes the earth to go around the sun). It seemed good to them to divide each month into smaller units....28 is divisible by 7 =4....It's also divisible by 4=6...or 8=3....We could have had 6 day weeks or 3 day weeks...But they thought 4, 7 day weeks per month best.

Ancient China and the Far East had for the longest time 10 day weeks as they had calculated the lunar month at 30 days...so 3 weeks per month. But finally gave up and joined everyone else in the 7 day week.

Barely 200 years ago the French created the French Republican Calendar with ten days in the week.

The Indian calendar never had a week. We used to follow PAKSHA - a fortnight. Shukla Paksha starts from the next day of Amavasya till Poornima and then till Amavasya it is Krishna Paksha.

weeks of between four and ten days have been used historically in various places.