Why were sub-saharan africa tribes or ethnic groups somewhat isolated?

Thesis statement for negative effects on immigration

Which of the following statements would be supported by both a communist and a utopian socialist? a) a government should restrict the number of imports and exports to protect its gold reserves b) governments have no right to restrict the actions of businesses or customers c) society will shift towards socialist ideals without the need for violent revolutions d) the gains of the industrial revolution should be shared by all members of society

Which type of constitutional power allows congress to regulate immigration and naturalization?