Complex sentence: So on 27 October 1956 France and West Germany concluded the Saar Treaty establishing that Saarland should be allowed to join West Germany, as provided by its Grundgesetz constitution article 23 and so Saarland did with effect of 1 January 1957, forming a state of Germany.
Split into simpler sentences: So on 27 October 1956 France and West Germany concluded the Saar Treaty establishing that Saarland should be allowed to join West Germany, as provided by its Grundgesetz constitution article 23. And so Saarland did with effect of 1 January 1957, forming since a state of Germany.