Why do we have so little information about the area before the arrival of arab traders?

What happened between 1804 and 1815

Hich explains why the constitution gave congress the power to create a system of federal courts? the constitution wanted congress to share power with the judicial branch. the constitution anticipated the need for courts lower than the supreme court. the constitution wanted congress to share power with the appellate courts. the constitution anticipated the need for courts equal to the supreme court.

Brainliestttme : ) -what reforms were made in communist china?