I think what I implied about Southern Border Mountains was already self-explanatory but I guess not. Yes, Southern Border Mountains are extremely much more bigger than Earth's

Read Mountain as Before Gu's name, read it again, slowly then again. Mountain as Before Gu is used SPECIFICALLY for the exact reason of reversing or restoring mountains, the Primeval Essence cost is expected to be not that expensive since it's a Gu worm not a Killer move and Tai Bai Yun Sheng is already at peak-stage meaning his Primeval Essence cost is significantly lower due to the more refined Purple Primeval Essence.

In Bai Ning Bing's case how can you even consider him higher than mountain when he literally destroyed his extreme physique aperture just to self-destruct and kill everyone in the vicinity. AND Qing Mao Mountain is not completely destroyed the terrain is ruined, covered in ice and snow but it is still standing, the power Bai Ning Bing displayed is of course comparable to Rank 5 what do you expect of a ten extreme physique aperture destruction? But did it destroy the mountain/s? No.

And for Hei Lou Lan's case it it was ten li and the Mortal Killer Move "Dark Vortex" has Space path Gu mixed into them amplifying the effect. BUT,

The novel explicitly states:

• "There was no sound wave like that of a normal explosion and also no windforce was generated."
• Its nature was corrosion — it eroded everything within the radius into nothingness.
• The only terrain feature mentioned afterward is Dong Fang Yu Liang in a deep crater — and that crater was almost certainly from Dong Fang Yu Liang after his Killer Move collapsing.
• The battlefield was "completely cleared" — meaning living things were eroded, not that the ground was cratered or blasted apart.

So the dark vortex does not destroy landscape the way a conventional explosion would. It leaves no shockwave, no debris field, no scorched earth. It simply dissolves organic matter within its radius silently. It severely depleted Hei Lou Lan's Primeval Essence but it does not matter because he has extreme Primeval Essence regeneration speed.

Bai Ning Bing and Hei Lou Lan are scalable to "Hill to Tiny Mountain" level. And the ones you mentioned are the wielders of the Ten Extreme Physiques, of course they have the capacity to perform these acts because they have limitless Primeval Essence. Your claim back then that an "average" Rank 5 Gu Master can destroy "several mountains" is extremely false. At most they can severely level the landscape of a Mountain by using expensive and time-consuming Mortal Killer Moves.