What was the nature of the alliances forged in the late 19th and the beginning of the 20th centuries?

Bismarck had built a complex network of international treaties whose key element was the Triple Alliance that united Germany with Austria-Hungary and Italy. The main objective of the German chancellor was the maintenance of a status that he considered beneficial for Germany.

what the first or next guy says

disease was the number one killer of native peoples. they had had little exposure to the diseases of europe. this led to some villages being almost completely wiped out and some tribes destroyed.