[Sawdring]

Bring small pox to the continent in 1015 and let them develop immunities and ways to call with it. Then let thee people develop and see what happens when the Colombus, Pizarro, and Cortes types venture into the Americas. Bring breeding populations of horse, goat, and cow with as well.

[cripplecreek]

Bring small pox to the continent in 1015 and let them develop immunities

While I can't produce a vaccine, I do understand variolation. Many would still die but there would be a significantly better chance of survival.