"BTW, no mystery at all about why trade stopped after 500!"What caused it? Muhammad, Muzzies, Muslims, Islam, and all other such words. Violent Arabs and their exorbitant thefts and baksheesheries."
Nah. It was the (worldwide) Dark Ages that began 540AD+-. Many, many people worldwide died.
There probably was some kind of global cooling darkening event circa 540, but the Genoese monopoly on the Arab spice trade is what had the Portuguese looking for a route around Africa in the late 1400s. The search for the source of the spice would send them around Africa to India and ultimately to a group of islands near Borneo, also to Brazil as an accidental by-product of their constant sailing around Africa.