What unite the islamic empire during the golden age of islam?

Quick and you will be picked brainleist1. people like stephen austin and others who made a deal with the mexican government to settle texas were known as 2.the were people who looked for gold in california and were named after the first year of the gold rush3. the area that became a state without first being a colony or a territory was 4.separate areas of land set aside by the federal government for indians were called