I was wondering this exact same thing the other day
why is it that Mexico Imports almost exclusively tar? where does the white come from exactly? I mean obviously it's called China White but is that where it comes from? Why is that an East Coast thing?
Coca grows best in humid/wet equatorial conditions of relatively high altitudes (usually around 2000ft about sea level or above, though generally not much more than a mile above sea level). Thus, it mostly grows in the geographical areas that can offer these conditions....which are few...