I know there isn't a definite single answer, but I'd like to know some factors that kickstarted Europe's 'age of discovery.' And out of all countries, why did it start off in the Iberian Peninsula?

We were just taught about this era in school but I was unsatisfied with the teacher's explanation. I felt it was too simplified, especially for high school. And, I'm skeptical about my teacher since she said that people (whoever that refers to) were still divided on wether the Earth was round or flat.

Anyway, here's what we were taught:

• The Ottoman Empire 'shut down" land trade routes through Asia.
• Muslim traders were jacking up the price.
• spices

I searched around past posts/threads but didn't find anything that quite answered my question. I know it's a very broad question but I hope someone can explain even a small part of it.

-thanks very much in advance!