The Wetlands of the Submerged

Hidden in a jungle in the south of the Indian Subcontinenant is thr Wetlands of the Submerged. It is a places that seems to sit on the border between reality and another dimension. Tales state that this region is a only a few miles by a few miles filled with various fantastic plant & animal species encountered nowhere else, along with dark mysteries and treasures.
Exactly what this other dimension is, is open to so many interpretations no one answer seems to fully fit. The closest seem to fit with the dreaded myths & folktales comcermimg both the Demiplanes of Dread and the Dreamlands. So far no-one can be certain.
What most seem to agree upon is that the wildlife in all it's forms seem to bear little similarity with any other wildlife in the surrounding regions. Also, a hazy mid0day mist seems to continually hang over it's hot humid surface obscuring those trying to peer too far ahead into it. Strange animalistic shrieks, growls, and other cries can be heard all around without the source ever being observed until encountered. The warm wind that gently blows at times brings the smell of flowers and other exotic plants through the air. The plants themselves seem to thrive in the hot humid enviroment, and bear the hallmarks of both jungle & wetland flora. A few are also terrifyingly carnivouris, either catching prey in oversized leaves when hairs are touched on them, or hiding pitcher plant style leaves out of sight for animals to drop in.
As for the animals, most appear similar to many insects and the odd lizard, just of far larger size and brightly coloured. Nearly all are armoured and are carnivours to some degree, with some feasting on plant material too. Fish and worms of various sizes infest the muck and water, the former feeding on dead organic waste, and the lattter again are carnivorous. Few birds are present and seem to be waders drudging up fish, worms or insects, orlarge predatory birds similar to hawks & eagles. Suprisingly many are coloured like parrots but without the same intelligent & inqusitive nature.
Those few that experience the Wetlands report that these animals are dangerous attacking most explorers on sight without thought or fear. But for this it isn't the most dangerous aspect of the Wetlands.
They report that after a few days in the Wetlands, all sense of direction and senses seem to start getting jubbled as if drugged. Whether this is by the miasma causing disease or airborne drug is unknown, though those that survive usually return with a handful of these too. Some of the diseases themselve seem to be quite predatory in their own way. Those that survive report finding the remains of previous expaditions scattered around, all destroyed, and the remains of the explorers lying scattered in the murky waters where they died. No one cause of death seems to be attributable.
Aonther point is stranhge totems hung in small dry groves similar to primitive native peoples of the world at large. Brightly coloured many are in the shape of humanoid & snake-like designs and great care seems to have been took in making & maintaining them.
Coupled with these being in or near small stone remains of what once appeared to be a massive stone city that seems to have sunk below the wetlants it adds a great mystery in of itself. This is especially true that the overgrown stones when examined show that they were worked and belonged to inner & outer walls of buildings. What markings there are appear to have Draconic & Primordial writing though little can truly be gleaned from these.
The latter point seems to be a stranger mystery as what has been able to be pieced together seems to mention the Serpent People, Leng, Mu, the Dreamlands, Kadath, R'Legh, Atlantis, and the Cavern of the Black Pyramid. Why, no-one can say.