The Leaden Ring is an amulet which allows its owner to enter and stay as long as he need in Mahakam. It is usually granted by the Elder-in-Chief of the enclave and it is considered particularly rare to obtain.
A Leaden Ring was granted by Elder Brouver Hoog to King Demavend III of Aedirn in 1250s circa when he managed to defuse King Foltest of Temeria from invading Mahakam, since the dwarves killed the tax collectors he sent in the enclave. Although Foltest's soldiers could have never taken Mahakam's fortifications, they would have surely organized punitive expeditions and pogroms against all the other dwarves in the Continent.
Years later, in 1267, during the Second Northern War and after the Lyrian golpe, Demavend gave the Leaden Ring to Queen Meve of Lyria and Rivia, who used it to enter in Mahakam and ask Brouver Hoog for reinforcement troops against Nilfgaard.