After examining several sites for a new plant to manufacture Buna-N, a type of synthetic rubber essential to the war effort, the German chemical cartel IG Farben chose a site near the towns of Dwory and Monowice (Monowitz in German), about 7 kilometers east of Auschwitz I. Tax exemptions were available to corporations prepared to develop industries in the frontier regions under the Eastern Fiscal Assistance Law, passed in December 1940.