Veramain
timbuktu
gold and salt
They owed their wealth of gold to those who provided them with salt, what mineral they lacked most.
Natural resources.
Adam smith
hunting and eating
The world may never know
The Feudal System which provided wealth and land to vassals, jobs for knights, and work for serfs.
L. Byllesby has written: 'Observations on the sources and effects of unequal wealth' -- subject(s): Wealth
John Dalton provided the basic theory about the nature of matter.
Thoreau believed that simplicity, self-sufficiency, and connection with nature were the true sources of wealth and richness in a person's life. He emphasized the importance of living deliberately and finding contentment with little, rather than chasing material possessions and wealth.
One of the largest sources was tobacco.