Thailand has had a long and complicated drug history with Burma and Laos, centered in the area where the countries meet at the Golden Triangle. The involvement of this area traces at least to the early 19th century although it was a mere bystander to the Opium Wars between Britain (let's sell as much as we can to support our imperial venture in India) and China (wait a minute, this is dangerous stuff and we should limit trade). It was from this area, it is credibly alleged, that Air America, a CIA front and successor to the famous WWII Flying Tigers, exported drugs from the region to raise funds to support the Kuomingtang nationalist forces after the revolution in China and later to support Laotian Hmong forces who fought on behalf of the U.S. in Vietnam.
The Golden Triangle's name supposedly comes from the fact that traders insisted on payment only in gold. Now there are two casinos visible from Thailand, one in Burma, one in Laos, both on former agricultural land. Most recently the poppy fields were destroyed and the farmers were encouraged to grow other agricultural products.
And here are some interesting facts from the Opium Museum at the Golden Triangle.
What more is there to say?