The Polish Brethren (Polish: Bracia Polscy) were members of the Minor Reformed Church of Poland, a Nontrinitarian Protestant church that existed in Poland from 1565 to 1658. By those on the outside, they were called "Arians" or "Socinians" (Polish: arianie, socynianie), but themselves preferred simply to be called "Brethren" or "Christians", and, after their expulsion from Poland, "Unitarians".