The legislation authorized two railroad companies, the Union Pacific and the Central Pacific, to construct the lines.
Reign of Terror refers to a period during the French Revolution after the First French Republic was established and it lasted from September 1793 until the fall of Robespierre in 1794. Its purpose was to purge France of enemies of the Revolution and protect the country from foreign invaders.
So, the Arab Empire was controlled by and based on religion. The mongol empire was based on the want for power. However the similarity between them is they both wanted to conquer.
The Kyoto protocol was an agreement led by the United Nations and signed by different countries on reducing their carbon emission to preserve the environment. The legal agreement stated that they would have to reduce greenhouse gas emissions by 5.2% to reduce effects of global warming.