STEP 1 (Upgrading Jayma's Hut)After you progressed a bit in the story, you'll be able to upgrade Jayma's Hut in your main camp. This will give you the ability to craft a long bow.
STEP 2 (Gathering the crafting materials)To craft the long bow you will have to go to the north and collect the following items in the snowy region.
14x North Cedar
12x North Black Rock
10x North ClayHITTING A TARGET FROM 70ft awayThe best way i found, is to go up to an undiscovered enemy camp. If you sneak up to them they should stay relatively still, making your long range shot fairly easy. Aim a bit above their head to compensate for the drop off of the arrow. If you stay hidden you can work out 2 or 3 misfires and get it on another target if you miss one.