Originally part of Kievan Rus, Belarus was part of the Polish-Lithuanian Commonwealth until the Polish Partitions in the 18th century. After over a hundred years of Russian rule followed by seven decades as a constituent republic of the USSR, Belarus attained its independence in 1991. However under authoritarian rule it has retained closer political and economic ties to Russia than any of the other former Soviet republics. Belarus and Russia signed a treaty on a two-state union on 8 December 1999 envisioning greater political and economic integration. Although Belarus agreed to a framework to carry out the accord, serious steps towards implementation have never been undertaken. Belarus has the "honor" of being one of the last authoritarian states left in Europe.