The Union of Lublin in 1569, united the Kingdom of Poland and the Grand Duchy of Lithuania as one single state, the Polish–Lithuanian Commonwealth, and thus the "Sejm" was supplemented with new envoys from among the Lithuanian nobility. The Commonwealth ensured that the state of affairs surrounding the three-estates system continued, with the "Sejm", Senate and King forming the estates and supreme deliberating body of the state. In the first few decades of the 16th century, the Senate had established its precedence over the "Sejm"; however, from the mid-1500s onwards, the "Sejm" became a very powerful representative body of the "szlachta" ("middle nobility"). Its chambers reserved the final decisions in legislation, taxation, budget, and treasury matters (including military funding), foreign policy, and the confirment of nobility.