You first meet Quickhand Zhang in Phantom Blade Zero's Crimson Forest and, assuming you free him, arriving at the Thieves Camp and his first hideout, he quickly recruits you to find his counterparts and unmarked treasure in each region.
I've included videos below of where to find Zhang's hideout and the jade treasure chest locations in each region, plus corresponding text entries that explain what you'll need to do to reach each in terms of battling enemies or grabbing any keys required.
