Hey there mate!
Steel is 5160 that's been differentially oil hardened for a harder edge and softer spine. Rockwell range along the edge would be 55-57 rockwell which is hard enough to provide a great deal of stability when chopping but not so hard that it forces you to use whetstones or diamonds etc to sharpen. Easy to get up to fine form in the field. The steel is also professionally tempered, which even though ti's quite a basic process we're still the only nepalese makers that do it.
Andrew and the team at Kailash