How do countries get their names?

Some are obvious: The Philippines are named after Spain’s 16th-century King Philip II, and Bolivia is named after the Venezuelan revolutionary Simón Bolívar. Israel is another name of Jacob, thought to be the patriarch of the Jewish people. Mauritius is named for Maurice of Nassau, the 16th-century Netherlands magistrate, and Swaziland is named for the Swazi people, who are said to get their name from the 19th-century king Mswati II.