וימח את כל היקום אשר על פני האדמה מאדם עד בהמה עד רמש ועד עוף השמים וימחו מן הארץ וישאר אך נח ושאר אתו בתבה
“All existence on earth was blotted out—humans, cattle, creeping things, and birds of the sky; they were blotted out from the earth. Only Noach was left, and those with him in the ark.” (Bereishis 7:23)
Noach's generation sinned so extensively that Hashem had no choice but to completely destroy the world and start again. Only Noach and his family, along with a small number of each species, were found righteous and permitted to survive the flood inside the teivah [ark], and from them the world was repopulated after the flood ended. However, although the Torah seems to say that all people other than Noach and his family were killed in the flood, the Medrash (Pirkei D'Rav Eliezer 23) teaches that Og also survived the flood, and Tosfos (Niddah 61a) adds that Og's brother Sichon did as well.
These two giants lived until Moshe defeated them in battle more than 800 years later, just before the Jewish people entered Eretz Yisroel (Bamidbar 21:21-35). Although more than 30 non-Jewish kings were killed in the battle for Eretz Yisroel, there is a particular stress placed on thanking Hashem for the defeat of Sichon and Og, as Dovid singled them out in Tehillim (136:19-20): L'Sichon melech ha'Emori ki l'olam chasdo, l'Og melech ha'Bashan ki l'olam chasdo - for (the death of) Sichon the king of the Amorites, for Hashem's kindness endures forever; and for (the death of) Og the king of Bashan, for Hashem's kindness is eternal. What was so unique about Sichon and Og that warrants this emphasis on thanking Hashem for their defeat?
Rav Gedaliah Schorr explains that Sichon and Og represented an unparalleled force of tumah [spiritual impurity] in the world, and as long as they were still alive, it was difficult for Moshe to properly teach the Oral Torah. This is alluded to in Parshas Devorim (Devorim 1:4-5), which states, “After Moshe had smitten Sichon king of the Amorites, who dwelt in Cheshbon, and Og king of Bashan, who dwelt in Ashtaros in Edre'i; on the other side of the Jordan River in the land of Moab, Moshe began explaining this Torah." The Torah juxtaposes these two seemingly disparate concepts to teach us that only after Sichon and Og had been killed was Moshe able to explain the Torah in 70 languages (Rashi). What made their tumah so potent and powerful?
After Noach exited the teivah, Hashem promised him that He would never again flood the world (9:11), which is difficult to understand. When Hashem brought the flood upon Noach's contemporaries, it was because He saw that the world had become so corrupt that it was necessary to start over. Although this was negative for those who were killed, it was actually beneficial for the world. If so, what was the value of Hashem's promise to never again destroy the world? If the world does not reach such extreme levels of immorality, there would be no need to bring a flood even without this promise, and if the world does become so corrupted again, it would be in its best interest to be decimated and recreated. If the best thing for the world is to be destroyed, why would Hashem promise to refrain from doing so?
Rav Yisroel Reisman explains that Hashem's promise to Noach was that He would never again allow humanity to sink to the level of moral decay that it reached prior to the flood. Up until that time, people were capable of perverting nature and the world around them to such an extent that a flood was necessary to restore order. After the flood, Hashem informed Noach that the human capacity for both good and evil would be diminished, and it would therefore no longer be possible for man to corrupt the world around him to the degree that a flood would again be warranted.
With this insight, Rav Yisroel Reisman explains that Sichon and Og were unique in that after the deaths of Noach and his family, they were the only humans in the world who were born prior to the flood. They were able to live for more than 800 years after the flood because they were born in the antediluvian period when such lifespans were typical. However, as a result, they also retained the unparalleled ability to create exceptional moral decay that could damage all of nature. This explains why Sichon and Og possessed a powerful spiritual impurity that made it difficult to transmit the Oral Torah, a tumah which was eternally erased from the earth through their deaths. For this reason, it is appropriate to single them out and specifically praise Hashem for eliminating them and their destructive potential from the world. (R’ Ozer Alport)
