Disciples of Enlightenment
- is Dai Viet
It is before 1500.
In the Disciples of Enlightenment achievement, starting as Dai Viet you attempt to convert/release nations to the Mahayana faith, racing to do so before 1500. The achievement requires 10 other nations to adopt the religion: The player’s country itself does not count.
A straightforward strategy to get the achievement is to mostly ignore your neighbors in Indochina and focus on tiny island nations in Indonesia. Take exploration ideas, explore the South China Sea, revealing Tidore, Ternate, Luwu, Buton and Makassar. Start colonising a province in the lower Philippines when Sulu spawn. Use that colony to get same sea-tile adjacency, allowing you to fabricate a claim on them. Once you have the claim, cancel the colony. Core Sulu and then begin converting it to Mahayana. Having cored Sulu will give you colonial range to colonise between Tidore and Ternate. Again, use the colony to get adjacency to fabricate claims, then cancel the colony once you have the claims. Again, core and convert them. Finally send the colonist to lower Sulawesi, again using this to get adjacency to fabricate on Luwu, Buton and Makassar. Core and convert them. A colonist in north Taiwan will allow fabricating claims on Ryukyu. Finally, using the rival CB will allow you to force convert Champa, which in combination with releasing as vassals Tidore, Ternate, Luwu, Buton, Makassar, Sulu, Ryukyu, Annam, and Tonkin should get you to 10 nations of the Mahayana faith.
To start, ally and get military access to Pangasinan in the northern Philippines. Pangasinan already starts as Mahayana, and count towards the achievement. However, their sole province is Animist, so watch out for Animist rebels who may attempt to convert them. Take loans and build a fleet of at least 15 light ships, going above forcelimit, as losing a naval battle in the archipelago can result in your armies being paralyzed.
After allying Pangasinan, transport your army into their province. Declare a no-casus belli war on Tondo while promising territory to Pangasinan. Tondo will call in Maynila and any of the other Philippine OPMs they may have allied. In cooperation with Pangasinan, defeating Tondo+Manila's army should not be a problem. At the peace table, give the province of Tondo to Pangasinan, and annex the rest.
From Mindoro, claims can be fabricated on the rest of the Philippines, and the run becomes a matter of picking off the minors with the least allies. Once the OPMs are conquered, release as many of them as necessary as vassals (keep in mind to release Lanao before Maguindanao, as the latter starts with a core on the former) and force-convert them to Mahayana via subject interaction. Alternatively, their capital provinces can be converted prior to releasing them, which will also set them as Mahayana.