I'm sure I've referenced this chain of events before as questions about the Dalai Lama are pretty common in r/AH and this is all tied into the formative periods of the Dalai Lama institution itself.

I. Historical Context

So, some background information, which again I've definitely discussed before but I can't find it right now and I need more coffee.

There are four sects of Tibetan Buddhism, the first and last are the most relevant for our discussion here:

• The Nyingmapa, "the Old Ones," who, before they were the "Old" ones, formed during the Tibetan Imperial Era (630-841 C.E.) and then were on soft-boil until the 1200s.

• The Kagyupa, "the Oral Tradition," which has four major and four minor subsects. The most famous is the Karma Kagyu, headed by one of the two Karmapas, and another, the Drukpa Kagyu, is the state Sangha of Bhutan and will come up briefly here.

• The Sakyapa, "the Gray Earth," which were once the de facto Kings of Tibet under Mongol sovreignty (1258-1364) and were dethroned by one of their own lieutenants, Jangchub Phagmodrupa, who reigned as the new de facto King while the Mongols dealt with the Ming Uprising (and lost, obv).

• The Gelugpa, "the Virtuous Ones," who had their origins in the Kadampa sect started by the Indian Pandit Atisha, who came to Tibet and preached, starting a popular lineage of teachers including one Lama Drom. The Kadam were reformed by "the man from Onion Valley," yes, that's literally his name: Tshongkhapa. And from then on his followers were known as "Gelugpa."

One of Tshongkhapa's later disciples was Gedun Drub (1391-1474), who became a famous Lama in his own right and constructed, somewhat ironically, the now famous monastery that serves as the throne for the Panchen Lamas, Tashilhunpo. The recognition of reincarnate lamas (tulkus, Tib. sprul sku) was actually disapproved of by Tshongkhapa, but the ball had already starrted rolling for more than a couple of reasons and was hard to stop. Tashilhunpo passed to Gedun Gyatso, Gedun Drub's reincarnate, and then it passed to Sonam Gyatso.

Up north, the various Mongol tribes were all reliving the glory days of Chingghis Khaan's Empire. The early pathetic phase of the Northern Yuan, when Mongols were sitting around hearths bragging about how the Ming pretender was actually a Mongol bastard, and one day the North shall rise again, was over. Mandukhai Khaatuun and her husband Dayan Khaan had managed to whip them into shape and fought the Ming to an uneasy truce, but at least managed to stabilize the situation. Their grandson, Altan Khaan, by 1521 had managed to conquer a good half of the Ming's northern borderland and was on his way towards establishing Hohhot as a forwarding base to continue campaigns into China.

Of course, he was hardly the last Chingghisid alive at that point, and needed some added legitimacy and spiritual empowerment to his reign and the coming wars. The Sakyapa, (see above) who had a previous relationship with the Mongol Khaans (specifically Khubilai Khaan, a direct ancestor of Dayan and Altan) were still highly regarded Lamas, but out of power. The real religious authority in this post-Mongol pre-Dalai lama Tibet were the Karmapas. So Altan sent a message to the Karmapa Lama to ask for his approval, but received back a polite refusal. (This is probably one of Tibetan History's great turning points...) For whatever reason, someone suggested the famous Lama Sonam Gyatso, who gladly accepted. (My personal theory is that Gedun Gyatso, Sonam's predecessor, was well known for shamanic practices, which is of course something that the Mongols were really into, though I need to look into this more.)

Sonam Gyatos arrived at Altan Khaan's camp and they had a lively discussion, which involved Altan's request that Sonam declare him the reincarnation of Khubilai Khaan, and for Sonam to accept him as one of his root disciples so they could recreate the relationship between Khubilai Khaan and his Tibetan Lama, Chogyal Phagpa. Sonam agreed, and made a very public ceremony, endowing Altan Khaan with all of the spiritual power and authority of his direct ancestor. And in an unexpected return, Altan Khaan turned towards his new Root Lama and declared him "Dalai Lama." "Dalai" being the Mongol word for "Ocean," a direct translation of the Dalai Lamas' inherited name "Gyatso." (rgya = vast, mtsho = lake.)

Bam. The institution of the Dalai Lamas had started, and the Mongols, or at least those under Altan Khaan's rule for the time being, had now become not just Buddhists, but Gelugpas.

Once Sonam Gyatso died, a reincarnate needed to be found. And if there's an argument to be made for all this reincarnation business to be political and have nothing to do with spirituality, here it is. The Gelugpa Lamas in charge of finding his reincarnate, just so happened to find him in a newborn grandson of who else but Altan Khaan himself? The boy, Yonten Gyatso, was raised a Mongol, and spent a lot of his life doing shamanic rituals that mixed Buddhist tradition and Mongol native religious tradition (Buddhism has always been a syncretic religion, especially in central Asia). And he had a lot to do with spreading Buddhism while his family was busy expanding their empire and influence through central Asia. More than his father's Qoshot Tribe would be converted to Gelugpa Buddhism, most importantly and fanatically, the Dzungars. But more on them later.

Yonten Gyatso died in 1616 and his reincarnate was found in a young boy from the wealthy Zahor Clan. Again, continuing the whole "reincarnation is political" theme here, Lobsang Gyatso was a logical choice. The Zahors were well-connected (including to a rival for the Ralung Throne, whose competitor had fled to Bhutan and was setting up a series of fortresses literally while Lobsang Gyatso was being recognized, kicking off a Hundred Years of war between the world's highest countries), wealthy, and relatively powerful. The boy who would soon become known as Lobsang Gyatso failed the famous test where a child is supposed to recognize a bunch of objects from his predecessor's life, but the Lama went outside and informed the search committee that he had recognized them anyway. Throughout Lobsang's education, this was held over his head. In his Autobiography, the Fifth Dalai Lama claims that his teacher told him repeatedly, "You didn't pass the test, so you must work extra hard." When he was being brought to Lhasa in a palanquin, a man who had a conflict with the Fourth Dalai Lama, Yonten Gyatso, bowed towards the boy, but Lobsang Gyatso didn't acknowledge him. This was regarded as a recognition of their conflict in his past life. But Lobsang Gyatso later wrote, (paraphrasing), "I was a child. Truth be told, I recognized no one."

Let's ignore the paradox that the man Tibetans regularly refer to as "The Great Fifth" (literally, lnga pa chen po) was himself skeptical of his own rebirth, and yet one of the great candidates for the success of the tulku system as a political one.Tthe Mongols, or at least the Qoshot Tribe, were so far into the Gelugpa camp that their leader, Gushri Khaan, the new leader in the line of Temujin-Khubilai-Dayan-Altan, was a fanatical supporter of the new Dalai Lama. Though in the 1650s, the Qoshot had refused to join the Manchu in their war on Ming China and were in fact looking at the chaos as a possible opportunity to conquer China for themselves. The young Dalai Lama, more eager to have the aggressive and antsy Mongols away from causing any trouble in an increasingly dire political situation in Tibet and the Himalayas (the war with Bhutan was not going well, and the King of Tsang was becoming increasingly unhinged about it) gave his blessing for the Qoshot to conquer China. But at the last minute, they went west instead of east and conquered Lhasa instead, dethroning the King of Tsang, and then summoning Lobsang Gyatso to the Divine City to take his destined place on the Tibetan Throne.

Lobsang Gyatso was pretty upset (at his Regent for approving of the plan to take Lhasa without consulting him... or so he claims, victors and writing and all that) but, well, one doesn't just tell the man waving a sword and in control of a bunch of religion-crazed horse archers "no." And as their Lama, figured he might be able to calm the situation. He went to Lhasa and, well, did calm the situation. Gushri Khaan was crowned King of Tibet, but immediately gifted all of it back to Lobsang Gyatso, the 5th Dalai Lama.

We won't go over the 5th Dalai Lama's reign. The short version is that Bhutan thought that he might be a good candidate to bring the war to a close, but instead he supported his cousin and the wars intensified. The Nyingmapa, Kagyupa, and Sakyapa were all allowed to operate essentially without change to their normal operations, while some smaller sects - the Jonangpa, Borangpa, and Bonpos - saw their monasteries closed, their texts wrapped in cloth and buried, and their monks forcibly sent to other sects. The Qoshot took up residence by Tsho Ngon (today's Qinghai, the lake). And in Lhasa he opened up the first fire department, settled Muslim merchants into the city who asked for some land to build a mosque, increased trade, settled peace with the Manchu in 1653, established the first medicinal college in Tibet, and started construction on the Potala Palace, Tibet's most famous landmark.

Then he died.