I'm surprised nobody mentioned 1492 in Spain: -The Inquisition was born. -Columbus made his 1st voyage to the Americas. -The last Muslims in Iberia were defeated. -The large Jewish population of Spain was converted or expelled. -Spain was united under a single monarchy. Each of those points had a huge impact on world history. Taken together, 1492 Spain must be the biggest turning point during the OP's time period.