Before the Spellplague, the Brotherhood of the Red Tide ruled the Pirate Isles.
During the Spellplague, an unnatural storm caused by the echo of Mystra’s death across the planes captured, in a sense, many of their ships and crews and they were dragged to the Elemental Chaos. Now they inhabit the Red Shoals of Dkar (Dungeon Jan10- to be published) where they ply the treacherous seas within a perpetual chaos storm that rages across the plane.
Islands within the storm, known as the Red Shoals of Dkar, form a home base from which these pirates light out to attack seaside settlements and ships of the mortal world before sailing back to their home base on the Elemental Chaos, loot in tow. These pirates have unique knowledge and magical prowess that lets them safely navigate these storms, making the Red Shoals like Shipwreck Cove on steroids.
The co-location of the Isle of Jagged Teeth on both Toril and within the Elemental Chaos means that the Brotherhood now has a way back to Toril but also a way to escape the Elemental Chaos.
Of course, the Brotherhood is changed. Many are now abyssal genasi.