Following the 1939 invasion of Poland, in accordance with the secret protocol of the Molotov–Ribbentrop Pact, Nazi Germany and the Soviet Union partitioned Poland into occupation zones. Large areas of western Poland were annexed by Germany. Some 52% of Poland's territory, mainly the Kresy borderlands—inhabited by between 13.2 and 13.7 million people, including 1,300,000 Jews—was annexed by the Soviet Union. An estimated 157,000 to 375,000 Polish Jews either fled into the Soviet Union or were deported eastward by the Soviet authorities. Within months, Polish Jews in the Soviet zone who refused to swear allegiance were deported deep into the Soviet interior along with ethnic Poles. The number of deported Polish Jews is estimated at 200,000–230,000 men, women, and children.