The defeat of Og, the king of Bashan, stands as a major and distinct achievement during the conquest of the land. His story is separated from the accounts of other defeated kings [מלבי״ם] to clearly highlight that the Israelites successfully took possession of his entire domain [מצודת דוד]. This conquered territory included the complete region that was under his direct authority and control [ביאור שטיינזלץ].
Og was not an ordinary ruler. He was the last surviving member of a group known as the Rephaim [ביאור שטיינזלץ]. These were actual giants who struck deep fear into the hearts of anyone who encountered them. Their name reflects this terrifying nature, as the mere sight of these massive figures would cause people's hands to go weak with dread [מצודת ציון]. From his seat of power, Og ruled over his kingdom through two main capital cities, Ashtaroth and Edrei [ביאור שטיינזלץ].