Mountain is the 4th tier biome. You should already have explored the swamps and obtained Iron gear before heading up there. Killing Bonemass isn't required. You definitely want your best foods active too.

Wolves hit hard and fast. Block or dodge, though you're best off getting them from range while they're unaware.

Stay out when its dark when you're first exploring, any star wolf is likely going to rip you apart. You'll also want Stamina meads and the eikthyr buff. You'll be running and jumping a lot on the slopes and stamina can be a major worry.