Before an assembly was formed to protect the rights of roman plebeians, the roman government was controlled by

Wealthy Patricians  

Explanation:

The patricians formed the elite of Roman society and descended from the ancient founding clans of the city, from which derived the expression "patrício", patres-familias. The structure of the Roman government was for most of its existence wholly or mainly occupied by the patricians. In Republican positions, especially in the Consulate and in the Senate, were the most illustrious patricians. In addition, the patricians were large holders of arable land, from which they derive their main wealth.

The patricians had many privileges in Roman society, moreover, they controlled the government for a long time and established unjust obligations to the plebeians, until an assembly was formed to protect the rights of Roman plebeians.

profound political, administrative, and social changes in the british isles.