This is based on the description of the Hydra in Blood Enemies for most of what is below, so if you have the book, check out pages 42-45 for a description of the domain, the Hydrakin, and the Caracdir.
There are four provinces that make up the Harrowmarsh
Abbreviations: Hy = Hydra's Guild (Bereak the Hydra)
Here is a brief description of the provinces
[edit] Waterfjord
This province is home to the Hydra itself. It is deep in the Harrowmarsh and is comprised only of swamps. It is the furthermost province from dry land, and is situated right at the end of the Asarwe River on the coastline. To move into the province requires a boat or barge. Armies are unable to invade as they can not move in large enough numbers to be of any use. It is possible to move troops through the province but there is nowhere for them to land without sinking into the swamp.
The province is home mainly to the Hydrakin. There are thought to hundreds of the monsters here, as well as large numbers of crocodiles, and snakes. The province is also home to the Hydra at his tower in Waterfjord Tower. Although it mainly keeps to itself, any who visit are sure to make their way into the Hydra's stomach. Boats traveling down the river have also disappeared occasionally.
There are also a few small human settlements in the province, home to maybe 50-100 fishermen and pirates in each. These settlements are known as Althlone Island, Younghal Harbour, Drogheda Bay, and Westpoint. Each is comprised of huts sitting on stilts above the swamp, surrounding a central platform. Also each village has 5-10 fishing vessels or small rafts tied up to their houses.
The village of Westpoint is also thought to be home to a mage and alchemist known as Dwynaa the Bose. This ancient sorcerer is a friend of the lizard men and trades with them for the animals and plants he needs to make highly effective and fast acting poisons. He can sometimes be found in anywhere from Rohrmarch to Binsada selling his wares.
This province is the most northern of the four provinces, bordering the Brecht kingdom of Rohrmarch. Home to the Caracdir it is a place little visited by Humans. The main Caracdir village is a settlement built onto a hill, known as Toree. Several hundred of the lizard men live there and Toree is walled and protected by a dozen warriors at all times – with more rushing to the sound of the alarm within minutes. The province is still very swampy and small boats or rafts must be used to move around.
The Caracdir use these rafts, or they can swim or wade through the swamp. A favorite tactic of theirs is to hide beneath the swamp with only a nostril peaking above the surface of the water. This makes the lizard men almost invisible and they can easily ambush travelers. The Caracdir eat humans so travelers are advised to take the road north of the swamp, rather than end up in a Caracdir's cooking pot. Although Toree is the only known Caracdir village they are found throughout the Harrowmarsh and there are thought to be at least a thousand of them scattered throughout the four provinces.
[edit] Sodden Falls
Once part of Binsada this province has long been abandoned by both Binsada and the Hydra. As the driest of all the four province it is rarely used by the swamp creatures that inhabit the rest of the Harrowmarsh. Many islands of dry earth and rock dot the province so it is possible to invade and capture it, provided you had enough vessels to move your troops from one small island to another. The province is however home to a large number of bandits, who run the Hydra's Guild (also found in Binsada and Sendoure).
This guild is not believed to be owned by the Hydra itself, as most reputable scholars agree that the Awnshegh has little interest in other lands or money. Instead one of the bandits has set himself up as overlord of the Harrowmarsh. Baraek the Hydra as he is known claims to be the true Hydra and dresses up in a crocodile skin costume to scare his followers into believing him. It is also believed that he may be a Magician or Wizard as much of his appearance may come from illusionary magic.
Baraek has gathered a reasonable horde of 12 GB together and maintains a small army of 2-3 units of bandits which he uses to raid ships and caravans traveling down nearby roads. He also runs a protection racket among the citizens of the Harrowmarsh that brings in some money to his coffers. He prefers to remain on dry land though and spends much of his time in this province or in Sendoure.
Settlements in this province are much larger that the other three, with 200-400 living in each. They include Longfjord, Adelaide, Dundalk, Gweebarra, and Nenagh Birr.
[edit] Laughaure
The least populated of all of the Harrowmarsh's province. This isolated area of the marsh is also the most dangerous. Large numbers of Hydrakin and crocodiles roams the swamp eating anything that stands in their way. Anyone living in the marsh would find themselves open to constant attack from these monsters.
Despite this a few small human fishing villages exist on the coast. These are built similar to the ones in Waterfjord province, but are smaller with only 30-40 fishermen in each. The villages include Blackwater Sound, Chalky Inlet, and Laoghaire Point.