Answer and explanation:
A nation with an oligarchy form of government has a small, usually self-appointed elite, governing it. This elite may be distinguished by money, education, nobility, religion, or military power. It is common for this type of system to keep power in the hands of certain families, passing it down from to generation to generation. It is also common for the elite to govern in a tyrannical manner. Those, however - inheritance and tyranny - are not prerequisites for a system to be oligarchic. It is simply what usually ends up happening. In Brazil, for instance, after the independence from Portugal was declared as well as the republic was proclaimed, the government was, for many years, oligarchic. A minority of wealthy farmers from the states of Minas Gerais and São Paulo held the power.