Rashi: Also the city called "Ir Homiyah" (Yeshayah 22:2) due to its many people ? it is the great city, also it will bury its most valorous residents. There is no Mapik (Dagesh, i.e. dot in the) Hei because its name is Hamonah, like Homiyah.

Radak, Malbim: Just like the canyon is called Hamon Gog, so the city near the canyon or the city Yerushalayim will be called Hamonah due to Hamon Gog killed near it. Malbim ? this is to recall the miracle, and so people will guard from the Tum'ah of this city, like [the law of] a residence of Goyim. Via this, "v'Tiharu ha'Aretz."

Radak citing Targum Yonasan: Also there will fall the killed of the city Romi, that its clamor is great, and the land will be purified.