Blood and soil
Blood and Soil was a phrase and doctrine exploited by Adolf Hitler to provide moral justification for the elimination of the Jewish people.
Origin
Existing in the region long before Hitler, the phrase "Blood and Soil" itself serves as neutral expression. On a literal level it emphasizes nationalism and group of people's right to live on the soil (land) they descended from, but when used by Hitler it was applied to generalize the Jewish people as a race without roots or native land and therefore did not belong in Germany.
As a Nazi Ideology
Walther Darre popularized the phrase at the time of the rise of Nazi Germany. Darre was an influential member of the Nazi party and a noted "race theorist" and assisted the party greatly in gaining support among common Germans. The phrase was simple in meaning and it helped many Germans fully recognize some of the goals of the Nazi party as well as accelerating racism against not only Jews but foreigners.