how do they sharpen knives in remote areas of the world

[ChapmanPreferred]

I saw an old timer in Romania sharpen a sithe with a long stone from a near by stream.

 

[Bernoulli]

When I was in Colombia (long time ago), most men wore machetes and sharpened them on curbs.

 

[Ben Dover]

Actually, social anthropologists have documented stone, bronze and iron blades that were as sharp, or nearly so, as today's finest. The Scriptures relate that the prophet Samuel shaved his head with a sword. During that time period, most swords were forgedv from rather crude iron.

Necessity often causes even primitive peoples to adapt their crude and unsophiscated technologies to achieve quite sophisticated results.