A quick google-search didn't get me much. What are the Buhru mentioned on the Martyr's Gambit Black Market Brawl -item, do you think? A reference to something new? Other items make reference to factions; maybe the Buhru are some future faction or group we'll hear more about.
Just speculation, but the buhru are probably the natives of the blue flame isles? You can see an ancient temple here in the back of this illustration: http://img1.wikia.nocookie.net/__cb20140904230323/leagueoflegends/images/9/98/Bligewater_settlement.jpg
Another little bit of speculation they probably worship the mother serpent, the creature pictured in the bilgewater crest: http://1.bp.blogspot.com/-m-BiIuXGTyY/VYtcKdKOtfI/AAAAAAAAsT8/Gsar-fUrOKk/s1600/BWDB_crest.jpg
Since Fizzes race and the Marai are near Bilgewater, it is a high possibility of the original settlers being a sea related race.
