China, which was edging towards a industrialisation until the Mongols came along and wrecked everything.
Italy was the intellectual and artistic powerhouse of Europe throughout much of the mediaeval era, but its fragmentation into multiple city-states hindered it in playing an important political role.
Did the mongols really wreck everything or was It not rather the Mings of the mid 15th century or the backward Manchus ?
In my opinion, the Inca could have been great had they managed to resist the initial Spanish conquest (which is not unthinkable). Our POD is that the Spanish arrive before 1493 and Huayna Capac's conquests of the Altiplano and Atacama (which led to the Inca being massively overstretched, leading to decentralized military command for the north which IMO was one of the primary causes of their civil war down the road).
So basically the Spanish discover the Americas sooner and encounter the Inca in their prime, fresh off their victory of wiping out their only meaningful rivals but also before they do anything stupid. Because it's impossible to predict what would happen in any meaningful sense, let's assume the Spanish do manage to conquer the bay of Guayaquil but are unable to conquer Cajamarca in a ground invasion - in this scenario, the Inca make better use of their tactic of pummeling the Spanish in mountain valleys from geographical vantage points and are able to cause a stalemate to the point where the Spanish do not disrespect the Incan attempts to initiate trade.
At some point the Inca have to establish themselves as equals in the minds of the Spanish, so let's go out on a limb and say that there are farsighted Incan leaders who manage to secure trade deals for European weapons and naval vessels. The weapons are important for obvious reasons, to not be reliant on Spanish good will to survive. But the ships are even more crucial. It allows them to contact other nations, at the bare minimum the Portuguese and ideally either France or Britain - hopefully one of the three would be willing to trade with the Inca and/or offer security guarantees against Spain. Regardless, the Inca will need to be penned in on all sides by the Spanish (and the Amazon, where they were notoriously bad at fighting and entirely uninterested in) in order to establish a non-expansionist culture.
The ships are also important because the Inca do actually have prior knowledge of a land across the Pacific due to their contact with the Polynesians. It's entirely possible that they can pioneer a Pacific route to Indonesia if there are leaders who understand the value in doing so, and their objective after that would be to develop a stayover port, where they could host cargo ships from Asia as well as export some of their vast reserves of precious metals and gems in the Andes.
If you end up with a mercantilist Inca Empire in control of its own resources, they can cruise into the modern age in relative luxury, and there are many directions they could go from there.
Novgorod.
Poland-Lithuania.
Bulgaria could have overtaken much of the Byzantine Empire and replaced it with something younger, stronger, and able to withstand Arabs, Mongols, and Turks.
Burgundy.
Iroquois Confederation (Haudenosaunee)
Hanseatic League if they had become more centralized could have formed something like Switzerland and led the western explorations, could have even been the patron for Columbus instead of Spain. A friendlier Western conquest? Or just as barbaric.
Inca finding China before the Spanish get to them would be good, too. China imported all its silver IOTL from Japan and Spanish Mexico and Peru.
My first idea was to have the Inca successfully reverse the Polynesian immigration route and discover Asia in the 1350's, but after reading about the horrible boats that both the Polynesians and Inca had, I didn't think it was viable for them to have made that connection before the Europeans arrive.
Italy became "the intellectual and artistic powerhouse of Europe throughout much of the mediaeval era" because of its fragmentation; it's as if the leaders of the peninsula's small states had some sort of contest going on for centuries: each one of them wanted to be the best at the whole "patron of the arts" thing, since conquering everything in their sight (something Milan's Visconti and Sforza dynasties tried to do for as long as they were in control of the city, to no avail) would've been much harder. If Lorenzo il Magnifico or Ludovico il Moro would've been able to play Civilization back then, they would've attempted a cultural victory for sure.After the Italian Wars, the role of intellectual and artistic centre of Europe was taken up by the Netherlands, at least in part, and the Netherlands were, just like northern Italy, a highly cultured and urbanized (for the time's standards) society of city states focused on commerce.
Ah yes, didn't think of that. Still, even if a unified Italy would have been less artistically dominant than IOTL, I still reckon it would be in the front rank of European countries in this regard, due to its relative wealth, urbanisation and high population.
France without a demographic collapse and with the industrial energy of Belgium would have changed everything.
Polynesians probably did contact South America.
Can't you have competition between cities in a nation that would still lead to something similar?
Baghdad.
Kiev.
Xi'an.
Sultanate of Oman.
Ulaanbaatar.
Vienna.
Hungnam.
Oman? That sounds interesting, in what way could they have done better?
My gander was that if they westernised early on or had a stronger military they could've been a viable colonial state that becomes a much stronger power than OTL.