Cov hniav txiav, Cov khoom siv hlau uas tiv taus kev hnav siab

Tag nrho cov khoom yog ua los ntawm cov hlau boron zoo, tom qab forging thiab cua sov kho ua tiav, kom ntseeg tau tias cov khoom muaj zog txaus thiab hnav tsis kam. Cov khoom raug xa tawm mus rau Russia, Lithuania, Spain thiab lwm lub tebchaws, tom qab ntau qhov kev sim ua lag luam los ntawm cov neeg siv khoom, nws cov haujlwm ua haujlwm zoo yog thawj chav kawm.