The astragalus of a sheep is an irregular block of bone with four sides broad enough to land on, and on the steppe each of those four is named for an animal: horse, sheep, camel and goat. Every household that eats mutton produces them, so the material is free and universal, which is a large part of why the practice is everywhere from the Altai to Manchuria.
Cast in fours, the combination that lands is read. Four alike is the strongest result and is treated as a marked outcome; other combinations carry their own readings, and local traditions differ on the detail. The same bones support a whole family of games: flicking one bone at another across a table, shooting at a line of them, racing pieces along a track of them, sorting and matching them. Adults and children play, and the reading and the playing are not kept in separate compartments.
Sets are accumulated, kept in a pouch, dyed or polished with handling, given to children, and passed on within a family. A large old set is a genuinely valued possession, which is an unusual status for something that starts as a by-product of dinner.
Nothing is manufactured. The bones arrive from a slaughtered animal, are cleaned, and enter use, which means a household's set grows out of what it has eaten and can be replaced indefinitely at no cost.