Well, i think the answer would be : Standardized weight and measures
Standardized weight and measures first developed by the muslim merchants in Cairo. Before this standard, Length was measured by the length of one's body.
For example to measure silk, the usually used the term such as 1 arm length.
The thing is, many traders started to hire shorter people to measure this to gain profit , making exchange often became problematic
hope this helps
Indulgence - the term for the guarantee given to crusaders to avoid punishment of sin.
