Around 5 July 1941, Nebe consolidated "Einsatzgruppe" B near Minsk, establishing a headquarters and remaining there for some two months. The "Gruppenführer" determined that "Sonderkommando" 7a and "Sonderkommando" 7b and the "Vorkommando" Moskau would follow the Army Group Center, while "Einsatzkommandos" 8 and 9 clean up to the sides of the spearhead. In compliance, "Einsatzkommando" 8 reached Bialystok on 1 July, passed through Słonim and Baranowicze, and began systematic mass killing operations in modern-day southern Belarus (eastern Poland before World War II).