Native American tribes are grouped by the language they speak. For example, the Apaches are a group of several tribes that all speak the same language.
The causes of the Economic Boom of the 1920s were the Republican government's policies of Isolationism and Protectionism, the Mellon Plan, the Assembly line and the mass production of consumer goods such as the Ford Model T Automobile and luxury labor saving devices and access to easy credit on installment plans.
The note revealed a plan to renew unrestricted submarine warfare and to form an alliance with Mexico and Japan if the United States declared war on Germany. The message was intercepted by the British and passed on to the United States; its publication caused outrage and contributed to the U.S. entry into World War I.
An outlook or system of thought attaching prime importance to human rather than divine or supernatural matters