The government set up by the articles of confederation had

only a legislative branch, consisting of a unicameral Congress.

Explanation:

The structure of government of the United States under the Article of Confederation was unicameral because it has only legislative branch and executive and judiciary was absent. The main concern of Congress was that without any executive branch it was difficult to have effective leadership and it was weakly assembled. These problems later gave way for the three tired Constitution of the United States.