Kratom powder has been historically used in Southeast Asia for medicinal and energy-producing properties by chewing the leaves or making tea.
Traditionally, Thailand laborers would use Kratom in order to physically work longer and for mental motivation. It has also been used as a pain reliever substitute in Malaysia.
While Kratom has been used for these purposes for centuries in Southeast Asia, it has only started to become popular in North America and Europe since the mid-2000's.
Currently in 2015, the vast majority of the Kratom for sale today is from Indonesia. A smaller proportion of Kratom comes from Malaysia and Vietnam.
Indonesia is home to the most efficient Kratom plantations, as well as favourable exportation rules. Further, Indonesia has a very diverse range of different Kratom powder strains that differ quite significantly from one another.
This is because Indonesia is geographically dispersed in a way that creates multiple unique growing environments.
In the way that Florida is optimal for the growth of oranges, Indonesia is prime real estate for elite quality Kratom harvesting.
Although Kratom powder is indigenous to Thailand and has been traditionally used there for centuries, it is illegal in the country and has been for decades.
This was due to Kratom hurting other industries that the government profited heavily from.
Information from Wikipedia.org