Kayin was historically part of Burma until it was taken by the Empire of Thailand in 1931.
The Kayin Republic has limited recognition by members of the World Defense Federation. The Empire of Japan, Republic of California, Republic of Korea, Republic of Australia & New Zealand and the Seven Stars Archipelago are the only nations to give official recognition status as the Kayin Republic. The Kayin government has been fighting for independence since Sino-Thai War, when the Kayin was administered under Allied Sino-Japanese rule. When the allies withdrew from Kayin and Kuala Lumpur in the August of 1970, the Kayin people, who enjoyed the ethnic freedoms that were given under allied rule, feared the reunion with the rest of the Thai Empire, whose government officially discriminated against the Kayin minority. Many Kayin families fled to China and Australia as a result of the reunion. Those who chose to stay fought, both violently and peaceful, to gain independence from the Thai Empire.
After the end of the Sino-Japanese occupation of Kayin, the people of Kayin who chose to stay in the Karen State initially just wanted to secure rights for the Kayin People, not really wanting independence. The efforts largely failed as peaceful demonstrations often turned violent, especially near the soon-to-be capital of Kayin, Pa'an. Many Kayin and Kayin Rights supporters and scholars organized mass non-violent protests around major cities in the mainland Thai Empire. Many of them were successful, with the Kayin Anti-Discrimination Act of 1973 being passed, ensuring that the Kayin people are treated like any other citizen of the Thai Empire and that employers are not allowed to deny them jobs and housing and equal pay. Despite these successes, some mass protests, like the Karen Demonstrations at Bangkok, failed horrifically with fights breaking out between protestors and police, resulting in hundreds of arrests and injuries, as well deaths. These demonstrations were a turning point and wake-up call for many Kayin scholars and government officials: The only way to secure full rights for the Kayin people was to declare independence from the Thai Empire.
Declaration of Independence
In June and July 1982, the Kayin leaders drafted and signed the Kayin Independence Declaration, submitting it into the WDF and the Thai government. Enraged at this act, the Emperor of Thailand sent 3 regiments of soldiers to intimidate the Kayin leaders. The Kayin people were prepared though, with 3000 soldiers waiting for the Thai troops to arrive. When the troops did arrive, the Kayin Freedom Front initially allowed the Thai to come in, wanting to show the Emperor that they were not intimidated by the presence of Thai troops. This only further angered the Emperor who gave an order to storm the Pa'an Legislature under the the justification of "treason". The KFF quickly responded by opening fire on the Thai troops from hidden locations and even killing a well-respected commander of the Thai Empire.
Violence continues to rage across the states of Kayin, Kayah, and Mon as they continue to fight against the Thai government in order to gain full independence. Because of these random spurts of violence, Kayin is considered one of the most dangerous place to visit. Most travel companies won't even offer trips to Kayin because of this. Most of these firefights occur when Thai troops or police officers come across the Kayin-Thai Border, which the Thai government does not recognize. The streets are often filled with KFF, KLF and MLF, and MFF fighters armed with assault rifles and other weapons.
Kayin has a number of local allies who help in fighting the Thai government for rights of their people. A major ally and supporter of Kayin independence is the Mon States, who the Kayin have mutually helped to secure rights. The Mon also fought for independence at the same time the Kayin, but had less successes until the late 1990s.
Officially, the Republic of Kayin is a unitary presidential constitutional republic, as recognized by the countries Japan (and her colonies and realm), the Republic of Australia and New Zealand, and the Seven Stars Archepelago. Other members of the WDF do not recognize Kayin as an independent nation, but rather as a ethnic state within the Thai Empire. In practice, the Kayin state runs it's own independent government (albeit vehemently disapproved by the Thai Empire) that follows a constitution and has democratic elections. The states of Kayin, Kayah and Mon even go as far as refusing to send state representatives to the Empire of Thailand Prime Minister General Elections, claiming that "The Republic of Kayin and the Mon Republic are not part of the Thai Empire, but separate countries that operate different policies than the Thai monarchy."
Armed Forces and Law Enforcement
As a partially recognized country and one that is fighting for independence. The law and armed forces fall into the hands of military. Kayin is patrolled and protected by the Karen Liberation Front (KLF), Karen Freedom Front (KFF), Mon Liberation Front (MFL), and the Mon Services (MNS). Despite being having mainly military and paramilitary law enforcement, the Kayin Civil Police Services provides civilian policing made up entirely of volunteers. The World Defense Federation also provides peacekeeping forces to keep the violence from getting out of control.
The government of the Thai Empire still considers Kayin a part of the Empire; therefore claiming that Kayin is still under the law of Thailand and is protected by the Royal Thai Police, who the Thai Emperor has claimed were "wrongfully thrown out of their jurisdiction."