The need to connect Bangkok and sea ports to the American airbases in Isan - the north-eastern region of Thailand - during the Viet Nam conflict resulted in the construction of several quality highways.
As a side benefit, these highways resulted in that it became easier for people to go to and around Isan and in that goods could move around more easily.
So, export of surplus agricultural production became easy. Initially, this was primarily rice as can be seen in the national production statistics for 1960s and 1970s.
Isan at the start of the Viet Nam era was sparsely populated, so the increase in rice production was mainly a result of an increase in population as people migrated to Isan to convert forest and bush areas into rice fields.
Geographically, Isan mostly consists of the Khorat Plateau, which a trillion years ago used to be a seabed. So, the soil east of Khorat is mostly sand.
And as Isan farmers (unlike farmers in estuarine areas) suffer from a lack of water, the region is one of the poorest regions in Thailand.
On the bright side, the region can also be considered a bucolic paradise where watching the local wildlife is a pastime visitors can enjoy. But the many Isan women that flock to the bar beers in Pattaya, Patong, and Patpong are more interested in money than in staying at home in the countryside.
