Economic growth
At the core of Thailand's current political fault line is the country's changing economic dynamic.
Of the many changes that Thailand has undergone since Bhumibol came to the throne, the growth in the nation's economy is considered to be the most spectacular. Largely agrarian when he came to power, Thailand has since become an industrial and services sector giant in the region.
It remains one of the world's top rice producers, is one of the world's most popular tourist destinations and is a regional manufacturing hub for the auto industry and for hi-tech electronics.
However, with the largely rural and once-impoverished northeast of the country now at the center of a boom, its growing middle class in the rural region have been calling for greater political representation.
Economic growth in the northeast Isaan region hit 40% between 2007 and 2011, compared with 23% for the rest of Thailand over that period and just 17% for greater Bangkok, according to government figures.
Isaan, which once exported people to Bangkok and the rest of the world as cheap migrant labor, is seeing its workers return.
While the World Bank predicts that Thailand is on track to meet most of its Millennium Development Goals -- including eradicating extreme poverty and hunger, and improving maternal health -- income inequality and a lack of equal opportunities persist, especially between Bangkok and the rest of the country.
With an official unemployment figure of less than 1% of the population, Thailand could be seen as a model for other Southeast Asian countries.
Yet the plight of the country's estimated two to three million migrant workers -- most of whom are from neighboring Myanmar and fill many low-paid, manual labor jobs -- has gained international attention.
Most migrate willingly, but in June this year the U.S. downgraded Thailand to tier 3, the lowest level, in its annual Trafficking in Persons report. The downgrade means that Thailand has not met minimum standards in combating illegal migration and human trafficking and not made significant efforts to do so.
In a letter to CNN, the Thai government said, "Thailand has been actively combating human trafficking and the issue remains a top priority for the current administration." Acknowledging the downgrade, they added, "Thailand will continue to do our utmost to combat human trafficking and illegal migration."
Another ongoing challenge for the country is the Muslim separatist movement in the south of the country.
Over 90% of Thailand's population is classified as Buddhist, yet in the southern regions of Pattani, Yala, Narathiwat and Songkhla there is a Muslim majority -- Thailand government statistics put Thai Buddhists at just 6% of the region's population.
Muslims there have complained this Buddhist minority dominates the region, and many Muslim hardliners view the education system as a tool of Thai colonialism. As such separatist groups have operated in the region for over 10 years, according to NGO Deep South Watch, that monitors the conflict.
These politically motivated groups often target security officials and Thai government operations. According to the U.S. State Department, in March 2014, at least 50 violent incidents killed more than 30 people in these provinces; Deep South Watch put the cumulative deaths from related conflicts at around 5,500.
The Thai government has stated in a letter to CNN that "the problems in the Southern Border Provinces of Thailand have no direct linkage to religions ... [and] no direct linkage to any separatist movements."