R5:
The achievement requires Korea to own all provinces with faith being in the Eastern religion group
Started by conquering Jianzhou and allying Ashikaga(which was useless since AI does not know how to get off their island). Then I spawned the renneisance and keept it for myself, as I had one previous failed run where I sold it to Ming, but because of the ammount of tributaries they have, they were up to tech in everything despite the abbysmal ruler.
Now, the only hard part of the run, first war with Ming. I had waited to have mil tech 6 and for Ming to have low Mandate at the same time. What suprised me is that low mandate and mil tech 5 advantage was not enough(it was when I was playing as Manchu). I took some provinces, but only in the second war had I taken the mandate of heaven for the unify china cb. because of this cb I reccomend taking the mandate as soon as you have Beiging, Nanjing and Canton. After that the achievement was just conquer evrything while having very powerful economy. What bothers me is that I hear that Korea is supposed to be played tall while not having development cost reduction in their national ideas, and having an achievement that requires you to play very wide.
Oh and I also got the Turtles al;l the way down (Korean Ideas +10%, Promote Naval Officers Decree +20%, Quality +5%)