what changes in europe led to the "high middle ages"?

Answer 1

It may not be quite the right approach to ask what changes "led to" the High Middle Ages. This period term is simply a convenience, a rough historical division. In fact, many of the changes you can point to more DESCRIBE this approximate period than "led to it".

That said, you can look at TRENDS of and just preceding the 11th century to see a bit of 'how they got there' -- things like population growth and well-established towns, the end of threats in Northern and Eastern Europe (as, for example, the Vikings are converted to Christianity and the period of their raiding comes to an end). Much of this period is one of CONSOLIDATION and strengthening of more centralized powers -- from the emerging nation-states to the Catholic Church under strong popes.

This more settled period made it possible for the sort of cultural progress you probably are thinking about, including the great "12th century Renaissance" (in many ways much bigger and more important than the later 'classical revival' in the arts known as the Italian Renaissance), and the beginnings of the university system (12th century). But note that even a new development was not de novo -- it grew out of the monastery schools of the preceding period.

As I hinted earlier, a major key to the progress of "urban centers" -- that is, the growth not only in size but in ECONOMIC and POLITICAL organization (and stability) of the towns of Central and Western Europe. This included increased economic activity and trade (helped in the High Middle Ages by the development of a BANKING system).

Another key event, toward the beginning of this period, that helped greatly in shaping it was the beginning of the CRUSADES (First Crusade begun in 1095), which had not only religious repercussions, but major economic and cultural ones as it increased interactions (trade, etc) between Europe, the Muslim World and the Far East beyond.

Answer 2

I have studied a lot of medevial and renaissance history and never heard of High Middle Ages. What does this mean?

Answer 3

invention of the printing press: led to greater circulation of literature
improvements in warfare techniques