Europeans began to unify their measurement systems at the end of the 18th century during the time of Napoleon, as Napoleon found the chaotic measurement units of various European countries quite inconvenient while conquering Europe.
At that time, the various European countries followed France's lead, gradually unifying their own systems of measurement, and then, under France's promotion, established an international metric system across the continent.
In this matter, a certain Eastern major power had already achieved this over two hundred years before the common era, leading Europeans by a full two thousand years.
This world also faced similar issues; that is, among the countries of the Old World, each used its own measurement units, which was very inconvenient in international trade.
Initially, all of this would have been resolved with the development of the Industrial Revolution, as having a different set of units in each country was far too complicated to use.
