There is one easy way to get this after finishing the prologue, and obtaining this trophy.
. You will then be tasked with visiting Alexandria in visit of Aya. This is where you can obtain it (assuming you are of high enough level.)
The easiest/quickest way; Around the rivers and swampy areas of Sap - Meh Nome, (picture below) there will be many hippos residing around here. Find yourself a batch by scanning around with Senu, your eagle. The hippos will carry Hard Leather, so it'll be a skin symbol above them in the colour of green. Once found, just run up to the hippos and grab their attention, they will then automatically get drawn to you and attack you as they are naturally aggressive. Just run away and hide/get somewhere high until they go away. There'll be a visual/audio cue with a small-like flash on the screen, and you'll notice them getting bored and walking away. This is now done, so do it 2 more times.
Side note; if you're like me, though, you'll obtain this without even trying. I was just sailing on my boat, getting treaure locations done in the body of water in this region, and it just popped out of nowhere, didn't even know I was running away.