Answer:
The Articles of Confederation, created by Congress in 1777 and ratified as the forerunner to the U.S Constitution in 1781, established the legislative branch, in the hands of Congress, as the main government structure, given that it was the one where people were represented. For the main part, the executive branch, per se, was not yet established as it is known today, and it was very weak. Most of the decisive power was still in the hands of the states.
However, it must be said that originally, this Congress was not given either the powers, or functions that it has today, or that it had after the Articles of Confederation were changed into the U.S Constitution, later on. This Congress was the body that represented the nation in the central government, but it was more of a place where the different states exerted their power.