Because they wanted to get some pssssssssss
Answer: At the time of the exchange, there were contacts with each other, which was disastrous for the natives.
Explanation:
Contacts between Europeans and Native Americans were disastrous for the Indians. Coming to the New World, Europeans brought infectious diseases to which the natives had no immunity. Smallpox, flu, and similar diseases decimated the Indian tribes. A huge number of natives perished, and complete tribes disappeared.
It allowed books (ideas) to be printed en masse. Reformation vouchers were able to spread their ideals to many readers, causing many to be won over by their words. In essence, they outpaced their competitors.
Cars became popular in 20th century. I think this is the right answer.
In result of wet conditions and also poor hygiene, a lot of the soldiers would suffer from 'trench foot'. hope this helped :)
