Shadow Guardians were the most secretive organization. Even more so than the Shadow Order.
These two organizations only had a word in common but they were polars.
Not just in their ideologies, but even in their inception.
After the establishment of human alliance in 020 YAB, peace ensued for a few decades before a long-lasting war with intelligent sea creatures—Murlocs, broke out in 80 YAB.
Humans used their treachery and used the internal strifes to defeat the militarily superior Murloc race.
It was the classic 'Divide and Rule'.
But applying it subtly and carefully building up their own strength, humans took almost 120 years to exterminate the Murclos.
Of course, a few inferior unintelligent branches of Murlocs exist to this day. They were kept in separate islands and used for hunting.
When everyone thought peace could finally last, the consequences of the prolonged war finally caught up.