Human nomads of the Tolvan desert, these tribes are actually greatly numerous and only loosely interconnected. The one thing that ties them together, besides their dislike for sea travel and their unquenchable wanderlust (the latter usually overriding the former) is their skill and reliance upon glass, from household items all the way up to weaponry.
The Tolvid peoples prefer glass to steel, and have found ways of creating tools nearly as, if not more, strong as their metal counterparts. Sure, they are more prone to breaking over time, but this is not a problem when you have plenty of sand to work with.
OOC: Tolvid weapon proficiences take a penalty when using the same type of weapon in a non-glass form, but you can still use them. Glass weapons are slightly faster and require less edge maintenance, but after a certain amount of use, the GM will roll checks against the weapon’s breaking point. A broken weapon is about as useful as a broken beer bottle, and bad enough shatters can harm you or your party-mates (or your enemies, for that matter).
Replacement is easy enough; Tolvans are travelers and can be found pretty much anywhere, but things get more expensive and harder to find depending on how far you are away from the desert and/or from sand other than the deserts’.