Complex sentence: Monowitz was under the direction of the industrial company IG Farben-who were building a Buna (synthetic rubber) and liquid fuel plant there-and housed over 10,000 Jewish slave labourers, as well as POWs and forced labourers from all over occupied Europe.
Split into simpler sentences: Monowitz was under the direction of the industrial company IG Farben, who were building a Buna (synthetic rubber) and liquid fuel plant there. It housed over 10,000 Jewish slave labourers, as well as POWs and forced labourers from all over occupied Europe.