Nothing concrete here, just some ideas.
Zanj: Zanj is a natural trading nation, and their lack of nearby trading partners would drive them to explore and try to find new markets. Zanj could be a medium colonial power, with emphasis on colonising the East African coast and nearby islands. When the Europeans arrive they will envy Zanj's wealth and try to take it over, which will be a tough challenge for a country that's unused to war.
Japan: In 1419 Japan was a fragmented country. I suggest we make this even worse than vanilla by having several countries in Japan, some of which are Confucian and the rest Buddhist, with everyone getting cores on everyone else. It may well be that Japan is doomed to constant infighting or foreign domination (especially if it's still fragmented by the time great powers take an interest in it), BUT if somehow one of the daimyos manages to unify the country, Japan has the wealth and population to be a significant power. What if, instead of trying to cut themselves off from the outside world, the shoguns had engaged with it? We could make Japan's behaviour depend on which of the minors takes control, so it's a bit of a wild card - sometimes isolationist, sometimes colonial and sometimes extremely aggressive.
Sri Lanka: In real life Sri Lanka was divided, both politically and in terms of the ethnic mix of Tamils and Sinhalese. But what if the Sinhalese had stayed united, and the Tamils had never gained a foothold on the island? I see Sri Lanka as an opportunist power, one which becomes powerful by waiting for openings to arise and playing its enemies against each other rather than by brute strength. The religious and cultural divide from the mainland would make it difficult for them to become a great land power in their own right (naval power is another matter), but through deft diplomacy they could wield considerable influence over southern India. The great wealth of the island, and the fact that they are insulated from the turmoil of all the Indian minors fighting each other, would also ensure that they built up a decent tech lead compared to the Dravidians. If a strong Hindu power emerges, however, Lanka's little empire is likely to collapse as enough of an army is mustered to put an end to its meddling.
Zanj: Zanj is a natural trading nation, and their lack of nearby trading partners would drive them to explore and try to find new markets. Zanj could be a medium colonial power, with emphasis on colonising the East African coast and nearby islands. When the Europeans arrive they will envy Zanj's wealth and try to take it over, which will be a tough challenge for a country that's unused to war.
Japan: In 1419 Japan was a fragmented country. I suggest we make this even worse than vanilla by having several countries in Japan, some of which are Confucian and the rest Buddhist, with everyone getting cores on everyone else. It may well be that Japan is doomed to constant infighting or foreign domination (especially if it's still fragmented by the time great powers take an interest in it), BUT if somehow one of the daimyos manages to unify the country, Japan has the wealth and population to be a significant power. What if, instead of trying to cut themselves off from the outside world, the shoguns had engaged with it? We could make Japan's behaviour depend on which of the minors takes control, so it's a bit of a wild card - sometimes isolationist, sometimes colonial and sometimes extremely aggressive.
Sri Lanka: In real life Sri Lanka was divided, both politically and in terms of the ethnic mix of Tamils and Sinhalese. But what if the Sinhalese had stayed united, and the Tamils had never gained a foothold on the island? I see Sri Lanka as an opportunist power, one which becomes powerful by waiting for openings to arise and playing its enemies against each other rather than by brute strength. The religious and cultural divide from the mainland would make it difficult for them to become a great land power in their own right (naval power is another matter), but through deft diplomacy they could wield considerable influence over southern India. The great wealth of the island, and the fact that they are insulated from the turmoil of all the Indian minors fighting each other, would also ensure that they built up a decent tech lead compared to the Dravidians. If a strong Hindu power emerges, however, Lanka's little empire is likely to collapse as enough of an army is mustered to put an end to its meddling.