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What is the meaning of Chetzi Eretz Bnei Amon?
1.
Rashi: It is half of what [Yisrael] conquered from Bnei Amon
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and from Sichon.
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Yisrael took from Amon only what Sichon took from them! Surely Rashi refers to this; 'from Sichon' is what he owned before he took from Amon.