Her name indicates that she was from Cairhien, given the common Cairhienin ending -in preceded by a distinct consonant combination.
Nirelle was a strong Amyrlin, forceful and dynamic. Chosen in the belief that she would extricate the White Tower from her predecessor's foreign intrigues, she instead continued them, involving the Aes Sedai in a number of wars.
She personally led the Tower contingents in battle, a fact not seen in centuries. Had it not been for the war and the laws related to it, she might have been removed, but the Tower reaction to external threads was always to gather in and to do nothing that might even hint at any crack in the supposedly unbreakable facade.
During her reign, Stedding Tsofu was relocated and repopulated.