Thrór was King Under the Mountain from TA 2590-2770, and King of Durin's Folk in Exile from TA 2770-2790.

He refounded the Kingdom under the Mountain after leading his people back from the failed Grey Mountains colony to Erebor, following the deaths of his father (Dáin I) and younger brother.

When Smaug appeared in TA 2770, Thrór led the surviving dwarves into exile in Dunland, but he grew weary and dispirited. Ten years after the start of his exile, he went wandering in the wilderness, and by chance decided to enter Moria. There, he was killed by Orcs.
Encyclopedia entry originally written by atalante_star