Short answer: You've listed a diverse set of countries that have unique individual institutions that are largely unrelated to each other, with some exceptions. You've listed the Japanese Emperor (starting from the first millenium B.C.), Mao (who died in 1976), and North Korea and the Dalai Lamas, organizations that still exist. The common theme with all of the nations you've mentioned is Buddhism, and it's true that they all have some ideas of ideal Buddhist Kingship (cakravartin), combined with either Confucian ideals (China, Korea), Shinto tradition (Japan), western influence (Burma), or just rather bizarre historical coincidence (Tibet). The short answer to their isolationism is "reaction against westernization."

Long answer: the isolationism and divine kingship of the countries you've mentioned may be related, as it gives the authorities who would often issue policies of isolationism without lengthy checks and balances.

• Japan - the institution of the Emperor is the oldest (continuous) monarchy on earth. The Japanese Emperor, descended from the goddess Amaterasu, was literally divine until 1946 when the Emperor issued the humanity declaration. I'm sure it's possible that this sense of religious authority extended to some degree to the nobility and daimyo, leading to Japan's strict social hierarchy, though I'm not an expert on this area.

• China - China's concept of imperial authority extends back to the Warring States, or possibly earlier. China's mythical founder Fu Xi is followed by "The Yellow Emperor" who, like the Japanese Emperor and Amaterasu, point to a divine root to Chinese authority. Three thousand ears is a lot of history to go through, and I'm not a Sinologist. Suffice to say that throughout Chinese history, the Emperor was very concerned with Chinese economic control (more on this below). During the last 500 years, the greatest gift one could receive from the Chinese Emperor was free trade with the middle kingdom, to be granted by no less an authority than the Emperor himself.

• Joseon - Korea 1392-1910 modeled itself after Ming Dynasty China. They immediately abandoned Buddhism as their ruling philosophy, adopted a Confucian bureaucracy, and focused on internal matters.

• North Korea - This stems from both Korea's native tradition of Kingship modeled after Ming China, from the leftover remnants of Japanese Fascism, and Stalinist strategies of cult power and manipulation The lack of any competing influence or power other than enemies in the south and west has left the Kim cult unchallenged. It's worth noting here that Kim Sung-il's uncle was a Protestant minister and in The Cleanest Race you can see how Protestant Christian illustrations of their religion has influenced Kim Dynasty propaganda. I.e. they literally modeled their regime after religious portrayals.

• Tibet - I can talk at length about this for quite some time, since I am a Tibetologist. Probably the biggest reason the Dalai Lama is acknowledged as a "god" or a "god-king" at present is because of confirmation bias. The Dalai Lama was the most powerful of Tibetan tulkus (Tib. sprul sku) since 1913 when Tibet declared independence, and he's been even more powerful since his exile in 1959, ballooning in both international prestige and among the Tibetan exile community in 1989. That said, the Dalai Lama's power is entirely based on tradition. He has since (in the early 2000s) renounced all political power, and in the 1700s and 1800s, it was still very much an open question over how powerful the Dalai Lama was supposed to be (in often open competition with the Panchen Lama). Before that, the Dalai Lama had a measure of official power, starting with the 5th Dalai Lama, Lobsang Gyatso, but even that is based largely on the fact that he had powerful patrons (particularly the Qoshot Khaan, Gushri, and the Manchu Shunzhi Emperor) and was a renown scholar. Before that, the Dalai Lamas were merely religious teachers whose authority was granted by the amount of followers they had (not dissimilar to today). The Dalai Lamas, technically speaking, aren't even the head of their own religious sect, the Gelukpas. That authority falls to the Ganden Tripa (the head of Ganden Monastery), which is a rotating position among high-ranking Ganden khenpos, often tulkus. (Think of it like this: the Dalai Lama is often compared to as "the pope of Buddhism" but he's more like a very powerful bishop whose authority has grown based on historical circumstance, while the actual pope who determines doctrine has shrunk from power. That said, the Dalai Lama was still looked upon as a god-like figure, being a powerful incarnation of the Bodhisattva of Compassion, Chenrezi (Skt. Avaloketishvara). Though not all of the people we would define as "Tibetans" thought the same way, (or even still do, for that matter). The Dalai Lamas' authority only realistically extended through south-central Tibet in the region known as "U-Tsang." The eastern and northeastern provinces, Kham and Amdo respectively, have historically been resentful of Lhasap political influence, or outright hostile to it. There's pretty much no basis for Dalai Lama rule in Amdo (ironically, where the current Dalai Lama was born), and though a few were born in Kham, eastern Tibet has historically had a number of small kingdoms that have historically been Nyingmapa strongholds, coming to blows with Gelukpas especially in the latter parts of the 19th Century. Most of our western texts regarding Tibet come from the first half of the 20th Century, when Lhasa was at the height of its political power and seemed to be on the rise. Most of those writers (Heinrich Harrer is the most famous, he of Seven Years in Tibet fame) never seemed to be outside of the Dalai Lama's authority. I.e. they were almost always in U-Tsang, and hardly ever in Kham or Amdo. Tibetologists like Giuseppe Tucci or Sam Van Schaik often have different perspectives on Tibetan history because they traveled to Dunhuang, north of Amdo, or Kham (it's either coincidence, or carefully designed, that current Visas to historical U-Tsang are very difficult to get, while visas through Amdo [modern Qinghai and Gansu] and Kham [Sichuan] are as easy as a normal Chinese visa).

• Burma/Myanmar - I've either lived, read extensively on, or studied the countries above. But here I have to confess total ignorance, and rather than submit a hypothesis, I'm going to admit that I don't know where Burma's concept of authority and kingship comes from except that it certainly begins with the Buddhist cakravartin theory... and that's all I know.

Cont'd.