system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did the world come to a common consensus as to what day of the week it is?
gpt
To make a very long story, short (human history). Through the expansion of empires that forced the standard upon the conquered and through trade routes that agreed upon a standard in order to plan out shipments.

Missionaries to 'uncivilized' natives also contributed to this standardization.