Relatively new patch, new wrinkles on an older achievement. Madyas is a two-province republic that sits with Cebu and the rest of the gang in the Philippines. Apart from a tributary and Cebu, they are the only Hindu nations until you hit Majapahit down south. This is important because the Dharma patch changed up how religion works. You used to spend a relatively small sum in missionary maintenance per month to convert a province. Dharma jacked up the prices and tied an exponential cost to the province’s autonomy; a recently conquered heathen province of decent worth would have you spend 3-4 ducats a month for at least 2 years. This period is enough to easily bankrupt a 2 province minor looking for early expansion!
Early game Madyas can’t go on a conquering spree until you spend your monarch points on boosting your capital and in turn your per month income. You want to, anyway, so you can keep up with tech once the Renaissance hits. Anyway the usual method of taking Exploration and colonizing the South China Sea is your main pathway to building your power base and kicking ass.
Now the Sun Invasion achievement is a tricky sort. If you have cores of at least 5 provinces within a Colonial Nation Area they are automatically converted into a Colonial Nation and those provinces are no longer owned by you. There are two ways around this. The first is basically set up the Colonial Nation with all four provinces, let them become an independent nation, then declare war on them once the truce expires in about 5 years. That went against my greedy side, wanting to keep everything under my control for the entirety of the game. The second method is to set up Colonial Nations on both sides of the Area of Mexico and hand them all the provinces I didn’t want during my conquest of the Aztecs.
Castile unfortunately grabbed harder at Mexico than I did and had control of the three northern provinces I needed. Rebels broke away Mexico and Tlapacoyan in the 1600s so I could snap them up without fighting them AND Great Britain at the time. By the time I fought this last war over Huastec, Castile was not allied with them but had much of Australia and North America under their thumb. A lot of it burned!