Not merely black sand, but sand of ground obsidian — volcanic glass.

Made: c. 2,000 years before year zero (First Age), by Atlas, joined to Svarog’s arid crater-land.

Story

Atlas spread a great desert across the south-east; with Svarog’s arid land around World’s Breach it became the Obsidian Desert. In the same years Svarog raised the Black Mesa above it.

Around year 200 an empty suit of obsidian plate stood up out of its sands — the Doombringer, later the Hollow Knight — and Atlas raised the Orcs here, living for glory and war, with their warrior order, the Sandborn. Around year 300 Atlas raised an army in the south-eastern desert, and around year 400 founded the orcs’ War Camps. Around year 500, late in Age II, Sylvanus made the south-eastern desert grow crystals — small, obsidian-like, born of hot sand and dry air, amplifying magic; the first mines opened, and Glaive Port became the nearest walled city to them. The Doombringer raised the orcs a second army.

Around year 600 the Hollow Knight led both armies against Glaive Port. The orcs who stayed said that is not the way: they gathered the crystals of the sands and fused them into a great obelisk in their central war camp — the Final End.

Now

The desert orcs, good but fanatical, keep the Final End; the war camps have no armies left. The crystals are still mined.

Connections

Open: [?] the Lost City is hidden “somewhere in the former desert” — which desert, and why “former,” is unknown.