Product of the Cold War it seems,
On 1949, US government received an official confirmation that the Soviet Union had developed a Nuclear bomb.
To maintain the upper hand, President Truman approved the development of the hydrogen Bomb, an equivalent to 500 Atomic Bombs.
Indentured servants is the correct answer.
These are usually people who wanted to go to the new world, but are too poor to finance themselves for the trip, and so they agree with a person on the amount of time they would work for their 'master' in exchange for a "free passage"
hope this helps
Germanic tribes such as the Franks, Ostragoths, Vandals and the Visigoths were surrounding it and weakening it by spreading into their territory, and also it was having internal governmental issues and struggles for consolidation of power.
The Mexican society wasn't united, since they were constantly fighting with each other. Since soldiers were killed, they also lost military power. When the Spanish arrived, they had a strong military, but also diseases, which killed Mexican soldiers. That made the home society vulnerable.
Have a nice day! :)