Circa 1500s-1600s;
Polynesians make contact with the Inkas near the Galápagos Islands as both groups expand in the Southern Pacific near South America. Initial relations are cordial, but to put it simply neither side has anything the other wants; the Inka are a massive, almost collectivists bureaucracy that provides more than ample amounts of food, clothes, etc for all their people. On the other hand, the Polynesians are sea-born explorers and early colonizers. Finding a land with a strong centralized state that is heavily populated is not what the Polynesians are looking for or want.
Ming China explores the Southeast Pacific, making indirect contact with the Inka via the Polynesians. With the Polynesians acting as middle men, the Inka and Chinese exchange goods, mostly crops - maize, potatoes and peanuts to China, and wheat, millet and rice to Inka. However, the Ming would be mostly focused on the areas closest to them, and if they explored the Pacific far enough the would eventually discover Australia - a much closer, and less densely populated and weaker organized, and larger land-mass much more situated for colonial goals, IMHO. Its highly doubtful that the Ming, or the Siberian or Transbaikalian Russians would make contact with OTL California, Columbia, etc. Alaska is a possibility, but there's nothing there worth investing in - and thus no reasons to continue to explore south and find the better areas. IOTL the strongest reason for European exploration, colonization, conquest and imperialism in the Americas was the Spanish luck in discovering a fat, rich land in Mexico that quickly fell to their forces. Without that or an equivalent motive, there's no reason to make the same motives on the Pacific side of the Americas. IMHO, the Ming would have economic reasons to explore the southern pacific looking for the land from which the Polynesians were getting the trade-goods from the Inka. Finding OTL Australia would be a side-affect of this goal, in the same way discovering the Americas IOTL was a side-affect of looking for a new route to the Far East.
Islamic Mali lands near OTL Venezuela, northern Brazil and some of the southern Caribbean Islands, contacting the Carib and other seafaring peoples on the coasts. Lacking anything to trade back to the Mali worth the costs of the trip, the Mali spend time and effort colonizing the islands, and evangelizing the native populations, much like the Catholic European powers per OTL. Eventually the Mali make contact with the Maya city-states and the Mexica Triple Alliance.
Western European colonial powers contact the Mexica, Tarascan, Mississippi chiefdoms, Maya city-states, and various tribes, including the Haudenosaunee league, on the Atlantic coasts of the Americas, mostly North, as per OTL. Eventually they contact the Mali explorers, colonizers and evangelizes near the equator and south. This limits initial European exploration in that area, creating spheres of influence dividing the north and south Atlantic.
Eventually both the Islamic and Christian powers encounter the Inka in OTL Columbia/Ecuador. The Inka are expanding due to the population boom from the introduction of a partial southeast Asian agricultural package; seeing the Inka eating rice, millet, and etc, the European and African powers believe they have finally discovered an 'oriental' civilization.
