Monowitz (also called Monowitz-Buna or Auschwitz III) was initially established as a subcamp of Nazi Germany's Auschwitz concentration camp. It was one of the three main camps in the Auschwitz concentration camp system, with an additional 45 subcamps in the surrounding area. It was named after the village of Monowice (German: Monowitz) upon which it was built and was located in the annexed portion of Poland. The SS established the camp in October 1942 at the behest of I.G. Farben executives to provide slave labor for their Buna Werke (Buna Works) industrial complex. The name Buna was derived from the butadiene-based synthetic rubber and the chemical symbol for sodium (Na), a process of synthetic rubber production developed in Germany. Various other German industrial enterprises built factories with their own subcamps, such as Siemens-Schuckert's Bobrek subcamp, close to Monowitz in order to profit from the use of slave labor.