Final answer:
American Indians faced challenges like loss of land, introduction of new diseases, and cultural assimilation during European colonization. Immunity to new diseases was non-existent, resulting in high mortality rates, and the imposition of European customs and property concepts caused further displacement and cultural erosion.
Step-by-step explanation:
The challenges that American Indians faced during European colonization included a) Loss of land, b) Introduction of new diseases, c) Cultural assimilation, and to a lesser extent, d) encountering Technological advancements. The loss of land came about as European concepts of private property clashed with indigenous views that the land should be held in common. The introduction of new diseases such as smallpox, measles, and influenza had a catastrophic effect, as indigenous populations lacked immunity to these diseases which had been endemic in Europe for centuries. Cultural assimilation was forced upon American Indians as Europeans imposed their own religious and societal structures, often through coercive or violent means. While technological advancements from Europe did impact indigenous peoples, it was not universally negative and doesn't necessarily represent a 'challenge' in the same context as the other points.