The Kolkarun dwarves aren’t the wealthiest clan, but they are skilled negotiators and are one of the more active clans in the wider world. Some Kolkarun dwarves believe that their mythic founder was Kol Korran, though they don’t like to brag about it. They’ve established strong ties to Aundair, Karrnath, Zilargo, and the Talenta Holds, and Kolkarun diplomats played a critical role in securing Karrnathi support for recognition of the Holds. Kolkarun has had many alliances and feuds over the centuries, but always manages to trick others into fighting its battles. Rivals say “Kolkarun’s mother was a gnome,” and assert that Kolkarun dwarves are cowards and opportunists. The Kolkarun shrug and respond, “Only a fool passes up an opportunity.” Currently, they have strong ties to Mroranon, which relies on their support in the Iron Council and makes use of Kolkarun as ambassadors and spies, and they have maintained strong ties to Soldorak since the Exile. Many of the most powerful members of the Aurum are Kolkarun dwarves.
Kolkarun dwarves are the most adept sailors of the Mror. While they don’t focus their efforts on fishing, they have long been the primary sailors ferrying goods along Mirror Lake and facilitating trade and transit within the holds. However, House Lyrandar produces better ships than the Mror ever did, and today Kolkarun sailors are often licensed by Lyrandar. Kolkarun was quick to explore the Realm Below before the threat was known, but even they proved unable to negotiate with the horrors of the deep. Kolkarun holds a few outposts in Sol Udar—often with the help of Droranath mercenaries—but hasn’t made strong offensive moves in recent decades. Kolkarun dwarves are among those most likely to travel, and Kolkarun entertainers, sailors, and merchants can be found across Khorvaire. Most of the Iron Council’s spies are Kolkarun; the charlatan background works well for both clever merchant and freelance spy. Bard is a reasonable choice for a Kolkarun character, and they’re among the few dwarves with a true interest in lore.
Source: Exploring Eberron
Kolkarun shifts allegiance constantly. Its history includes feuds with each of the other clans at one point or another, and its allies change as rapidly as its enemies. Nevertheless, Kolkarun dwarves are shrewd entrepreneurs and charismatic negotiators, and their wealth allows them to supply potential allies with gifts. The other clans view Kolkarun as opportunists, while Kolkarun dwarves see themselves as smart enough to always pick the winning side. Currently, Kolkarun has diplomatic ties to Aundair, Karrnath, Zilargo, the Talenta halflings, and the Emerald Claw. It counts Mroranon and Soldarak among its allies in the holds, and for the last couple of decades it has maintained a growing feud with Doldarun, which seeks to discredit Kolkarun.
Source: Player's Guide to Eberron
During the Last War, Kolkarun was closest with Aundair and Zilargo.
Source: The Forge of War