query: SELECT ?item ?party ?district ?region ?start ?end
  WHERE 
  {
    ?item p:P39 ?statement .
    ?statement ps:P39 wd:Q14850694 ; pq:P2937 wd:Q90759969 .
    OPTIONAL { ?statement pq:P580 ?start }
    OPTIONAL { ?statement pq:P582 ?end }
    OPTIONAL { ?statement pq:P768 ?district .
      OPTIONAL { ?district wdt:P131* ?region .
                 ?region wdt:P31/wdt:P279 wd:Q10864048 . 
             }
    }
    OPTIONAL { ?item p:P102 ?partyStatement .
               ?partyStatement ps:P102 ?party. 
             MINUS { ?party wdt:P576 ?dissolved } # Party dissolved
             MINUS { ?partyStatement pq:P582 ?exitParty } # voluntary leaving
             } 
  }